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Old 08-11-2013, 04:35 PM
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Newbie follies - please help me learn from my mistakes

Help a newbie out. This is my first ever time painting auto paint. I used a turbine HVLP (I know that is not the favorite method but I have seen plenty make it work). 1.4 tip and Omni plus material (metallic base (silver) regular base (black) and MC270 clear. Pressure about 8-10 at the tip per manufacturer.

Overall it came out decent, until I tried to fix a mistake. The errors from the first go was the orange peal dust nibs, and some blotchiness in the metallic. Then I tried to repaint a section and it cracked all up on me (14 hours after first coats of base and clear .scuffed with gray scotchbrite pad the wax grease remover). Also I messed up on the gun set up (using the 3PM PPS System and l got paint in the cup (think I didn’t have it sealed right). So it’s hard to tell what the cause was, but I suspect it was my prep between the first paint and the repaint attempt – not the gun messing up (cause some of the other panels still came out okay).

The temps were in the 60’s. I set up a plastic lined booth and used a powerful fan blowing into the booth. Had decent airflow leaving the bottom on the opposite side (also I used a suit, face/respirator mask and gloves).

Things I think I did wrong

Keeping the fan going after I sprayed –maybe it allowed the material to cool to fast and not lay flat

I think maybe my coats could have been thicker. I was going to attempt that today. Seems like one of the new panels laid out nice. The one butted up to it (on the right) was one I did last night. I did a quick sand with 320 then 600 but there is still texture there.

Looking for thoughts on why it cracked up? What I could do to trouble shoot the OP I got (if my insight is off), and what I can do to take care of the dust nibs. I saw something on autobody forums about a nib remover – is that useful or even needed? Wets and/buffing? Lots of edges, though. What grit

Any thoughts or input will be appreciated. I will be using this cover to practice the dust removal and leveling OP. Not sure it’ll be worth it to sand it all down and make it paintable again. Or maybe I will use it. Not sure I want to paint the black and silver again. If I sand the bad spot the rest is done already. Seems unlikely I will get that prepped good enough to get paint to stick with all the raised lettering.

]

Left -fresh panel primed 3 days ago sanded with 320 then 600 dry. Right -panel with OP quickly sanded same way. Both resprayed with an attempt to goa little heavier than the first round


repaint cracking.



orignal base and clear - blotchy. Not bad, but it's there. I did try and do a "drop coat". One last spray little pulled back from the panel.



Was able to peal all the layers off - I think both layers, with my fingernail once it cracked up. I did use adhesion promoter before the original base and clear.





It was actually looking decent. When I did the letters I got some back on the silver and decided I would just repray that one side. Regrat that now ...the mistake wasn't that bad. Yet, this is all about learning though so I am trying to keep it inperpective!




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Old 08-11-2013, 05:13 PM
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Where in this world is the out side temp. In the 60s. I need to move there. I live in just out side of San Antonio, Tx, its been over 100 degs. every day for 2 F ing week now. I've had enough, I stopped painting on my Camaro because of the heat. Its hotter than YOUNG LOVE .
You must live up there in the great white north. Where everybody says OUT funny.
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Old 08-11-2013, 09:41 PM
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Where in this world is the out side temp. In the 60s. You must live up there in the great white north.
Yes sir, Alaska. Not great place for a camaro but it's fun for the 4 months I get it on the road!

So I was looking at some panels. The ones with the worst OP are the ones primed - and not sanded before paint. Maybe that was part of the issue. The OP is not nearly as bad on the cover as it was on the panels.



Still, it's there. Here is a pic of the base only from the second spray. I tried to move a little slower but I am not sure the gun was working correct due to the paint in the cup outside of the 3m PPS insert.



So with this situation do you want to lower the fluid amount? This would cause better atomization? Then I would just do slower passes? When I did my test pattern I did move back on the fluid volume. The center was still real wet ... not dripping, but real wet. That's what I want correct?
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Old 08-11-2013, 10:38 PM
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Okay. first, questions...how long did you leave the base coat between coat? What temperature of reducer did you use for applying the base coat? Omni MC270 doesn't require any reducer, just hardner...the mix ratio is 4 parts MC270, 1 Part hardner..did you add hardner to the clear coat...or did you add reducer?

You waited 15 hours and then sanded the clear and re-cleared the panel...the clear, even if it was mixed properly has not had enough time to set up or cure in order for you to repair a problem area. The dirt or imperfections, where they in the base coat or the clear coat? If they where in the base coat, allow the base coat to flash, use 600 wet paper and gently sand the imperfection out, dry of the panel, tack the panel and reapply base coat in the areas that you just sanded.

Keeping the fan running at those temperatures will not cause Orange Peel, if anything it will keep the base coat open longer and allow for better, more even flat finish of your base coat. If your gun is stet up properly, you do not need to apply paint thicker...that can cause Orange Peel. If your base coat is full of Orange Peel, your clear coat will have Orange Peel.

Again, the cracking, checking, wrinkling is caused by not having the clear coat cured enough to recoat it. At 60 degree, even if you used the appropriate hardner, it will not be ready to recoat for at least 24 hours...If you like I can get into a technical explanation...if you need that, let me know.

The blotchy base is gun set up and technique. When your spraying a high metallic silver, especially wit an Economy brand such as Omni, metallic control is difficult, even with good equipment. What you need to do is to slow down the speed of the reducer, say you paint a fender, move on to the hood, then you go back to the fender you just painted and apply a drop or mist coat. Stand back from the panel and duat a coat of your silver base over the panel. The panel will still be wet because you slowed your reducer down, the dusting will even out your metallic's, paint the opposite fender and repeat the dusting process on the hood. This should only be done after you have achieved coverage with the silver base coat.

If you don't sand your primer, the primer will have Orange Peel...that Orange Peel will be transferred to your base coat and your clear coat. If you base coat has not flashed...and at 60 degrees it will take a long time for it to flash...if you clear coat over unflashed base coat...it will trap solvents and peel...very Quickly.

I'll make you a deal. If your interested in getting your paint job looking good, doing it once (more). Let me know, I'll be happy to walk you through the process, one step at a time...even with Omni base coat, we can make your truck look like a million bucks.

I hope I answered your questions, I'm sure you'll have more and if you want my assistance, just ask...like iI aid, I'll be happy to help. I'll even tell you how to setup your Pint gun.

Ray
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Old 08-12-2013, 03:48 AM
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Originally Posted by 69 widetrack View Post
Okay. first, questions...how long did you leave the base coat between coat? - about 5-10 mins - until it was not tacky anymore - temperature of reducer - 70 degree reducer - Omni MC270 doesn't require any reducer, just hardner...the mix ratio is 4 parts MC270, 1 Part hardner..did you add hardner to the clear coat...or did you add reducer? - never got to the clear on day 2 - day one used hardner. Those came out okay - except for the OP.

You waited 15 hours and then sanded the clear and re-cleared the panel...the clear, even if it was mixed properly has not had enough time to set up or cure in order for you to repair a problem area. The dirt or imperfections, where they in the base coat or the clear coat? I was wondering about that - haste makes waste I guess - living and learning. Imperfections were/are in the clear (still need to get them out. I am going to use the first engine cover as a test/learning tool).


If they where in the base coat, allow the base coat to flash, use 600 wet paper and gently sand the imperfection out, dry of the panel, tack the panel and reapply base coat in the areas that you just sanded. - I did have to do this one time. Worked good - no evidence it even happened .

Keeping the fan running at those temperatures will not cause Orange Peel, if anything it will keep the base coat open longer and allow for better, more even flat finish of your base coat. If your gun is stet up properly, you do not need to apply paint thicker...that can cause Orange Peel. If your base coat is full of Orange Peel, your clear coat will have Orange Peel. - I saw somewhere online they said using a fan to dry could cause OP. Said it would flash the paint faster and not allow it to layout and flatten - thus my thought process. Gun setup - today, second try I dialed the fluid control back. I was about 1 3/4 turns open. If I did it more it seemed sort of "gunked up" in the middle of the test spray pattern. Much less it looked like it covered well but was almost dry looking immediately. Part of the problem is I have never seen a test pettern except for the few pics I found on-line. They don't do any justice I'm sure verse seeing it live. I'm guessing really.

The blotchy base is gun set up and technique. When your spraying a high metallic silver, especially wit an Economy brand such as Omni, metallic control is difficult, even with good equipment. What you need to do is to slow down the speed of the reducer, say you paint a fender, move on to the hood, then you go back to the fender you just painted and apply a drop or mist coat. Stand back from the panel and duat a coat of your silver base over the panel. The panel will still be wet because you slowed your reducer down, the dusting will even out your metallic's, paint the opposite fender and repeat the dusting process on the hood. This should only be done after you have achieved coverage with the silver base coat.
- hm, wonder if I should try a 60 degree reducer? The tech sheet says 5-10 mins and I would say the base coat was dry in less than 10 mins. I was moving my gun pretty fast though because the coverage was good. Maybe less fluid and a slower pass?

If you don't sand your primer, the primer will have Orange Peel...that Orange Peel will be transferred to your base coat and your clear coat. If you base coat has not flashed...and at 60 degrees it will take a long time for it to flash...if you clear coat over unflashed base coat...it will trap solvents and peel...very Quickly. - Stupid primer can said "no sanding needed if based within 24 hours". I did not take texture into account, only chemical interactions. Living and learning - won't do that again. question: the panels are painted wood (like a melamine). I'm not even sure I need primer. I think I could just sand off the glossy finish and base right over it. I actually did that with 2 panels the other day as a test and they are indistuguishable from the others.

I'll make you a deal. If your interested in getting your paint job looking good, doing it once (more). Let me know, I'll be happy to walk you through the process, one step at a time...even with Omni base coat, we can make your truck look like a million bucks. just an engine cover, a fuse box cover and some panels to airbrush art on - but I'm game !

I hope I answered your questions, I'm sure you'll have more and if you want my assistance, just ask...like iI aid, I'll be happy to help. I'll even tell you how to setup your Paint gun.

Ray
Thank you Ray - yes you got most of not all of them. I am interested, and I am going to give it another whirl in the next few day. My responses to your questions are above in bold. I really appreciate your (in depth) response, thank you. I think forums for the most part really enhanced the hobby world and you're a big part of that .

How can I tell a good test spray pattern from a bad? I know it's hard to decribe and seeing it would be ideal. If I fail again I'll have to go to a bodyshop and see what it looks like. I start with full air, and 2 turns out. That's almost full fluid. If I close down I can see when it's too dry (empty spaces between paint drops). Not sure when wet enough is though once it's covering?

I have a second engine cover, and I am going to get few new panels. Gonna start preppeing tomorrow or Tuesday (sand panels, remove lining maybe wash engine cover with soap and water. Hope to spray again Wed evening. Wifes Bday is Thursday so that's out, then going away for the weekend and it's starting to get colder. Supossed to be warm this week though so I am going to take advantage of it!

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Old 08-12-2013, 07:42 AM
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Well to start off with and no offense but, 2 turns this way, 1 turn that way on your paint gun doesn't really tell me anything, every gun is different. So here we go, your spray pattern should be about 8 to 10 inches long When spraying 6 to 8 inches away from the surface your painting. The pattern should look like and be a stretched out "0" with the same amount of paint being dispersed evenly throughout the pattern. A good way to check the pattern for being even is to first, tape a piece of masking paper to the wall in your shop/garage, spray a burst of paint on the masking paper. This will tell you if your pattern is that stretched out "0" that I was suggesting you need. If the patter is not a stretched out "0" and is heavier on the top and on the bottom, you have too much air pressure or not enough volume of paint for the air pressure at your gun. If the pattern shows that your getting more paint in the center than the top or the bottom of the pattern, you don't have enough air pressure or too much paint volume. If it's heavier on the top and the bottom of the pattern, first, try reducing your air pressure, if that doesn't give you the "0" effect, add more paint volume. Play with this for a while until you get that stretched out "0" effect you need.

Sounds simple, right...LOL...Your not done yet. To make sure that your getting an even amount of paint throughout the pattern, give your air cap a 1/4 turn. Now when you spray paint on your masking paper, the stretched out "0" should be laying on it's side. Holding the paint gun in a stationary position, spray paint on the masking paper until the paint starts to run. Yes, this is a time when runs are good. The runs should be even from the ends of the pattern to the center. By even, I mean that there shouldn't be a heavier concentration of runs at one end than the other. If the runs are more concentrated anywhere in the pattern, you have a possibility of several problems, they are, a dirty air cap, a dirty or bent fluid tip and or needle, a bad gasket allowing air either in or out of the gun where a seal is needed (if this is the case your gun will usually give you a spitting or surging sound while your spraying as well. If any of these things occur, clean your gun. check for a worn or bent needle, get a rebuild kit for your gun or replace it (sometimes a paint gun can be so far gone, old technology that doesn't work with today's paints or the repair kit costs almost as much as a new paint gun that it isn't worth repairing).

Okay, now your gun is set up, if you have any questions or need more explanation, let me know, I'll try and explain further.

Now, you said it was 60 degrees when you painted, you used a reducer rated for 70 degrees...so far that's perfect. The problem is the amount of time between coats of base. With cool conditions, a reducer that's rated for 10 degrees warmer conditions your flash times need to be 3 to 4 times longer, minimum. Even though base coat isn't "tacky" doesn't mean that it has finished flashing. Here is a test you can do to make sure that the base coat has flashed. Now, I realize that you aren't painting metal, your painting a plastic engine part but, there will come a time that you will be painting metal and this test will work for both metal and plastic. When you stick your finger in a cup of room temperature water and remove it, blow on it (blowing on it represents the exhaust fan your using)...what happens...your finger gets cold, correct, the same thing happens when you stick your finger into some reducer except the cold is more pronounced. If you apply base coat to anything, as the solvents are evaporating, they are cooling the object that you just painted...makes sense right? The test I do is to have another object that is room temperature close to what I'm painting, when the base isn't "tacky" anymore, feel the object you painted with one hand the other object with the other. When they are both the same temperature by feel, wait another 10 to 15 minutes before applying another coat of base or applying clear.

As we discussed earlier, Omni MC270 clear needs to set up longer than 14 hours in order to repair it, especially with the temperatures that you sprayed at. If you are not sure if it is repairable, keep some of the masking paper you used with clear on it and try and do a repair on that...if it works on the paper, it should work on the panel.

A fan running can cause Orange Peel....at warmer temperatures, not at 60 degrees using a 70 degree reducer. The only way a fan can cause Orange Peel at those temperatures using that degree of reducer is if you virtually have category 3 hurricane force winds coming off of your fan...if your fan is moving that much air, your not only going to get Orange Peel, your base coat is going to surface flash and trap solvents between coats of base, just as not letting it flash long enough as we discussed. Then after you clear the panel you just based, eventually the solvents will want to come out and take the clear coat with it...it will peel clear faster than showing a stripper a $20 tip. So the amount of air your moving needs to be enough to clear the over spray out of the paint room in a timely manner...if your moving to much air...these are the problems.

If your basing over top of melamine, it's a good idea to sand it, apply a coat of Epoxy primer and then base it. Melamine is a very hard product. Just like steel is hard, we don't apply base coat over top of raw steel, we apply an Epoxy over top of raw steel for that bond between steel, Epoxy primer and base coat. Epoxy primer is just what it sounds like...glue...with rust inhibitors in it. That glue part of Epoxy is what would give you the cushion between melamine and base coat. Many primers like Epoxies, have a recoat window that could be anywhere from 24 hours to 7 days depending on brand. If you want a flat finish on what you are painting and your primer has Orange Peel, your finish will have Orange Peel, so it's a lot like dirt in your paint, if you don't want dirt in your paint, don't put any in. If you don't want texture or Orange Peel, don't paint over top of something that has texture or Orange Peel, sand your primer/substrate smooth.

One more thing, if your doing lettering (I did see Chevy lettering in black)...paint your lettering first in black...allow even more flash time, mask of the lettering, apply your silver base coat, remove the masking from the lettering and clear coat the entire panel...don't know if that's how you did it but...that's the easiest way I have found.

Everyone paints different,,,I've worked with many painters and I always tell them to not try and imitate me and that they need to find that sweat spot that works for them. I can give you the basics, rules and regulations on painting and the usage of products. In the end I'm in Eastern Canada, your in Alaska and the gun is in your hands. I'll help you in any way I can and if you have more questions, and I'm sure you will, feel free to ask...I'll be happy to help.

Best of Luck and I hope I have given you answers to your questions.

Ray
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Old 08-12-2013, 02:40 PM
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Moderators, what Ray just posted should be a sticky.
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Old 08-12-2013, 04:04 PM
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Ray – first off I need to again say “thank you”. I hope that you realize what a help and positive impact you are having on us “new guys” by taking the time to provide such indepth and info loaded answers like you so graciously are.

Okay, on topic - I did do the paper on the wall spray pattern. I forgot all about the horizontal one to look at the drips. ]Will it really be an exact equal amount of paint from top to bottom? I would expect the top and bottom of the fan to be slightly drier verse say the middle or so. I guess I’ll experiment with adjusting paint flow and looking at the effect it has. Maybe it’ll be more clear that way to me.

Thanks for elaborating on the drying and assessing the flash. That is real helpful for me. About the primers. For now these are just “practice panels” for airbrushing so I’ll save the expense of the primer and just scuff it real rough for some tooth. Once I start doing work I’ll keep I’ll prime the boards. I didn’t have adhesion issues with the unprimed one but understand it might not show up until some time down the road. These panels will end up getting thrown away as trials anyway.

Masking the letters would be crazy difficult since they get quite thin. What another painter does and recommended was to use urethane “paint pen” to “paint” top of letters, and then clear. That’s what I did. What I didn’t do was put some masking around it. Slipped of and got the silver – that’s what led to the need to repaint that side However, it also led to this tremendous educational opportunity you are a large part of so it’s all good – again – thank you.

One more question – gun speed. At one point the hose got hung up and I stayed longer over one area. I thought I messed up bad going on too thick. Then it seemed to all flow together and that section came out nice. How do you know you’re at the right speed? There is surely a difference between just coverage and getting a nice coverage that “lays out”. Again, I know there is no substitution for experience and seeing it live, but if you were to describe what you see or are looking for as you spray (and in the immediate moments after) how would it go?
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Old 08-12-2013, 04:06 PM
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Moderators, what Ray just posted should be a sticky.
I couldn't agree more. This is the info I (and certainly other newbies) are looking for when I was searching the web.
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Old 08-12-2013, 05:12 PM
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Thank you both for the kind words and thoughts. My motivation is to offer advice that leads to a successful conclusion...I remember the people that took time with me when I was starting out. We didn't have a forum back then, we relied on one on one interaction. In some ways, that may have been better, in other ways, the access to information was limited. I've learned a lot from this site and just hope to contribute as well.

The spray pattern (runs), when turning the air cap 1/4 turn should be virtually even throughout the sideways stretched out "0". If your getting 3/4 of the pattern slightly drier on the top and the bottom, try turning your air pressure up slightly, Have you noticed your pattern when you spray thinner through your gun and leave the adjustment the way you would for paint? It's always heavier on the top and the bottom, that's because of the viscosity of thinner is less than the viscosity of paint. The more viscosity or thickness of the product, the more air pressure you need to break it up. If your getting a heavier concentration of material at the center 3/4 of your pattern, that would help explain the stripping or blotchy effect your getting in your silver base. We can discuss other ways to remedy that blotchy effect in another post...I don't want to give you information over load.

When it comes to sanding primer or prepping a panel, you have 2 types of adhesion, mechanical and chemical. Chemical adhesion occurs when the solvents (reducer) that are mixed with the binders and catalyst (hardner) in your paint penetrate the substrate that you are painting. By sanding the substrate you are in effect opening the pours of the primer/existing paint allowing the solvents to enter. These solvents penetrate the substrate drawing the catalyzed paint into the substrate. These solvent then need to escape, after they have penetrated they bounce back out through the fresh, still wet top coat. and evaporate leaving you a shiny finish. If you have not allowed the previous coat of paint to properly flash, your adding more solvents to a semi flashed top coat and will trap solvents underneath the top coat that you just put on and is starting to flash as well. If you clear over top of this (and it can feel flashed), the clear will start to harden but the solvents in the clear (I know that MC270 doesn't require you to add reducer, it's already in the clear) are going to try and release the solvents that where trapped in your base coat but, they can't escape because the clear is starting to set up and cure. What eventually happens is that the clear will peel off because those solvents will eventually escape taking the clear with it. I hope this explains chemical adhesion and the importance of allowing proper flash times. It may be a bit repetitive but, it's that important.

Lets talk about mechanical for a bit. Mechanical adhesion is achieved by sanding or roughing up a an existing substrate...lets say a quality 2 part primer...cured Epoxy or a 2K Urethane. The material that you apply over the sanded primer will bite in or attach itself to the footprint/footprints left by the sandpaper. When you use for example a 240 grit paper, you will have less sand scratches per inch than you would with say a 600 grit paper. The 240 grit scratch will appear rougher but, you have more scratches per inch with 600 grit for mechanical adhesion to happen...not only that but, similar to Orange Peel, if your substrate has Orange Peel, your top coat will have Orange Peel, if you have deep 240 grit sand scratches in your substrate, you will have deep 240 grit sand scratches in your top coat because the base coat that your spraying is too thin to fill the deep footprint left by 240 grit scratches. A rougher footprint will not always give you the results you want, adhesion or appearance. I hope that explains mechanical adhesion.

From your pictures, I couldn't really tell the size of the letters...a paint pen in this situation is fine.

Your last question is the question...its' the question of finding your sweat spot. I paint differently than most painters, I use about a 75% overlap and move faster...would I recommend this for you, sure, if it works for you...LOL. As I mentioned before, everybody sprays differently, different guns spray differently and experience is a wonderful teacher, when your trying to gain experience, getting advice and learning from the advice is your best tool. I always say, painting is a lot like golf...so much to remember...and trust me painting is easier than golf...for me.

I will tell you this, Omni's MC270 is a fairly thin clear and at 60 degree temperatures it will flow much faster and longer than at 70 and 80 degree temperatures. Put your clear on the way you want it to look, constantly looking where your going and where you've been. Your gun set up for clear will be slightly different than for base coat (even though Omni MC270 is a thin clear, it is thicker than base coat), but the same principals for adjustment apply. Remember the masking paper on the wall thing for adjusting your gun? Try applying clear to the masking paper as well. Push the product, by that I mean slow your speed down, practice your overlap, make several passes with the overlap that your comfortable with and let it flash...watch it flow out, apply a second coat (you may be surprised at what looks great in the beginning runs off the paper by the time it starts flashing)...when it starts running, remember the speed you where at and speed up until you get a speed where your applying your clear nice and flat and even. I've been painting for many years, when I try a new product, I still do this. It lets me know how fast or how slow I need to move to make the product flow without getting runs and maximum gloss. It may sound like a waste of material to figure out the best speed for flow but, if you don't get to know the product that your spraying, you can not only waste material by needing to redo it, the time in redoing it is also a waste.

I hope I've answered your questions, if you have more, feel free to ask...I'll help where I can.

Ray

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Old 08-13-2013, 03:44 AM
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Ray I re-read all you wrote again, beginning to end. I can’t thank you enough. I am going to take you up on your offer to ask more questions. If I am asking too much of you no worries, you have been more than generous with your time. If it all stops here you've provide more info and insight than I had hoped for already. However, if you’re still up for more here we go!

Questions – using your to touch temp assessment for flashing you said wait 10-15 mins after it feels the same temp and the control (non painted) piece. Is that a general rule of thumb you follow? That could be a lot of down time between coats. Within reason you can’t wait too long (not to exceed a few hours) between base coats correct? A longer wait is better? This is to assure there is no solvent pop or does it allow the paint to lay out better and reduce chances of OP?

Different rules for base verse clear? Clear should still be a little tacky when re-coating, correct? 2-3 coats of clear is a good place to be from what I gather.

Just to confirm, if my horizontal spray pattern is weighed heavy in the center drips (lighter on the edges) then I should increase air, or decrease fluid? Why do we even bother with the vertical pattern?

I’m still not 100% clear on what the coat should look like right after it’s laid down. I’m thinking it should be pretty flat and smooth, almost, if not right away. Is it normal to have some texture before it “lays down” or should it look like a smooth lake as soon as you finish your pass? The last pic in my 3rd post of the cover just base coated ... no good, should be smoother?

Is OP ever the result of too fast of a pass with the gun or too little fluid?
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Old 08-13-2013, 05:08 AM
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What in Good God's name are you doing up at ... let me do the math...1:45 in the AM? LOL. I get up early every morning, have for years...it's almost 5 AM out here and I seem to get a lot more done when the phones don't ring, people aren't coming for a visit and I get to think about my answers to you...LOL.

Great questions and I realize that sometimes confirmation builds confidence and confidence is what you need when you want to paint. So, to answer your first query, I don't mind at all answering more questions, I actually enjoy it. If you didn't ask more questions, I'd be concerned, I don't know off anyone that could become a painter and be 100% happy with the information received from 3 or 4 posts on a forum.

The waiting an 10 or 15 minutes is a rule of thumb and most of all, insurance. Flash times, especially with base coats are one of the most crucial processes to follow when painting. I have seen more paint jobs fail because of not allowing enough flash time and the clear falls off, sometimes years down the road because of trapped solvents. Even then, when you peel the clear off and smell the reverse side of the clear, you can smell solvent. House keeping and cleanliness is of utmost importance. When I do a "High end Job", I will spend hours cleaning and washing my paint area (booth). If you don't have a booth, you need to clean that much more for a dust free paint job. I have painted 1,000's of vehicles over the past 30 years, I have had 2 that where dust free...one was in a upper 5 figure down draft booth, the other was in a home made paint area, so it is possible.

In the best case cenario, the ideal amount of flash time is to base a vehicle or panel, allow about 45 minutes between coats for flash, make any minor repairs, remove dirt specks, even out metallic's (if needed) and let it sit overnight, come back in the morning, tack and blow the vehicle clean with your exhaust fan running, removing all dust and any thing that could land in your clear...wait at least 20 minutes and tack again and then clear the vehicle or panel. This is to ensure that all the solvents have dissipated from the base coat, it's still open and will readily accept being clear coated. Base coats usually have a 24 hour window in which to clear the based area...8 to 10 hours is well within that window. That is a lot of "down time" and most body shops don't have that luxury because the vehicles have to go and on to the next. That's why it isn't 100% necessary to wait that long, it's just optimum and in what I do, I'm not in that big a hurry anymore, I'm more concerned with longevity and the cosmetic appeal.

Clear should still be tacky when you apply your second, third, fourth, fifth coat of clear. The way to check is to touch the masking paper beside an area that you have cleared (I realize that you didn't use masking paper the last time but, touch an area of clear over spray close to what you just painted). When that freshly applied clear is sticky, when you remove your finger and you can feel that it is starting to set up, what other adjectives can I use...stringy, sticky, when it feels like it's getting thick, it's time for the next coat. Usually, depending on temperature, humidity and the additives used (Hardners and reducers if required) it will take a bout 30 minutes between coats.

If you have a heavier concentration of material in the middle of your pattern, yes, either increase your air pressure. I know that your gun requires 8 to 10 pounds at the gauge...that is a recommendation only if you go several pounds over that and get a proper pattern then do it. Also, I haven't seen many gauges that are 100% accurate, they can be out by a few pounds very easily and should be used as a reference point, not as a hard and fast, totally accurate piece of equipment. We bother with the horizontal pattern to make sure that the stretched out "0" is a perfect stretched out "0". Every time you use your paint gun, you clean it, if you don't clean it perfectly clean, dried paint material can be in your gun, in your air cap, on your needle and alter that "0" pattern, even slightly can make a difference. Look at it this way, if you cook, say Taco's and you prepare the hamburger in a frying pan...you wash it to make sure that it's clean. If you didn't, the next time you went to use that frying pan for eggs, well you might taste Taco's (kind of a wacky comparison but you get my meaning...although, eggs that taste like Taco's might not be that bad...LOL). Your paint gun is a precision piece of equipment, any foreign object can interfere with it's performance, that's why we test our equipment. Ask any painter that has been painting for any length of time, we've all learned the hard way, doing that White paint job and a hunk of Red or Gray something comes flying out of the gun because it wasn't cleaned properly from a previous job and it always lands in the middle of the hood.

Your base coat should lay down flat and when it has flashed it should look and feel like Satin. (Just on a bit of a comical note here, I had to spell check Satin...I originally spelled it Satan...had to chuckle, you definitely don't want it to look like Satan...LOL). Clear coat can have a little texture when you first apply it. Often it will flow out nice and smooth especially on top surfaces where your not as concerned about getting runs. On side surfaces it is more difficult to get that "like glass" finish...it is possible but does take much practice and knowing your equipment and material...remember the last post about learning your material and spraying clear on masking paper...your masking paper on the wall is hanging like a side panel...laying a sheet of masking paper on the floor wouldn't tell you too much...anybody can get clear to flow on the ground.

Yes, your base coat should be smoother. If your gun is adjusted properly, your material mixed properly, your substrate prepared properly (sanded with either 400 dry or 600 wet...using a sanding block) and you apply your base with even medium wet coats...it will lay down and flash like Satin...it will not have a choice but to lay down that way. That's why we have spent a great deal of time on gun adjustment...now might be good to spend a bit more time on sanding using a block. I'm sure you know what a block is, for those that don't, a block is a piece of equipment made of a solid material where the surface that holds the sandpaper is perfectly flat. If you are sanding with anything other than what I described, it isn't a block, it's a sandpaper holder...if you use guide coat to make sure that your panel is straight and your using anything other than what I described a block to be, it's an eraser. A good block will not only get the panel straight but, it will remove all Orange Peel from the primer, giving you a "smooth as a baby's butt" surface and that's exactly what you want. If you use a piece of sandpaper in your hand it will be difficult to get a smooth, flat finish because your hand is soft, and not straight and will contour into the crevices of the Orange Peel.

Another suggestion for you is that if your painting plastic pieces, a couple of coats of Epoxy primer between your plastic and your base coat is a good idea...just for adhesion qualities and that cushion effect that we have talked about.

"Is OP ever a result of too fast of a pass with the gun or too little fluid?" Yes, if you move to fast, or have to little fluid, your not going to get enough material on and it will not have a chance to flow or level itself. Always apply medium wet coats to achieve that Satin finish versus that Satan finish. Although, seriously, I have had to lay down a dust coat of clear and let it set up before applying a second and third medium wet coat on a new vehicle that had come in for repair in order to match that factory Orange Peel...so that should confirm that not enough material or moving to fast can cause Orange Peel.

Again, I hope I have answered your questions and again, feel free to ask more...I'm usually up at 5 AM at the latest...so now I need to get to work...LOL.

All the best and keep asking.

Ray

Last edited by 69 widetrack; 08-13-2013 at 05:24 AM.
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Old 08-13-2013, 01:10 PM
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What in Good God's name are you doing up at ... let me do the math...1:45 in the AM? LOL.

All the best and keep asking.

Ray
LOL - yeah, your calculations are correct, that's how I roll. Too many hobbies and not enough time for them all! Something has to give and lately it seems to be sleep.

Thanks for the response. It was again very helpful and educational . If they don't make this thread a sticky it'd be a real shame. I am sure there are thousands of people out there like me and this one thread alone could save someone hours of searching!

Anyway, my plan is to give her a go again tomorrow evening. It'll be a little warmer per the forecast, about mid to high 60's. Was going to do the base and clear in the same day - wait an hour or two between base and clear. I may reconsider and do the clear in the AM but I'll see how early I can get out of work and how long it takes me to base. These are mostly small insignificant panels and just an engine cover so it's not a major expensive job if it fails. It's really all to practice my spraying technique as far as I am concerned. Next spring I will be doing a spoiler and that will need to be done right - so I can re-do these then if need be - my "booth - PVC wrapped in plastic" is in my wife's parking spot and I think she wants it back .

Once again cheers to you and thanks. I'm going to make a quick run down of my visualized plan of action and throw it up later today or tonight. Maybe you could look over my proposed steps and comment.
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Old 08-13-2013, 01:48 PM
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LOL...Your learning about painting, me, I PM'ed "cyclopsblown34" to find out what a sticky was...LOL, so now I can thank you again for the kind words...LOL.

Mid to High 60's, even better for the material you have. I hate to raise your paint budget but the only flaw I see in your material is your primer...went through your posts and couldn't find what type of primer you used...that information would be great to know.

Throughout this thread I've been discussing that the quality of your substrate will determine the quality of your finished product. That means not just preparation, it also means what type of primer. Your dealing with a hard plastic, you need a cushion between the plastic and the base coat in order to get the adhesion situation looked after. An Epoxy primer over top of the sanded plastic (with adhesion promoter) would work best...as I mentioned, Epoxy primer is basically a glue (in this case the rust protection this primer offers wouldn't be an issue...it's plastic after all) and can be top coated with or without sanding. Some Epoxy primers sand well, others don't. PPG's DP line of Epoxy primers is one of those that just doesn't sand well, PPG does make an Epoxy primer in their Essential line that does sand fairly well but I believe it only comes in gallons. If you wish I can recommend an Epoxy that comes in quarts and does sand well...just PM me and I'll give you the information...unless the primer that your using is an Epoxy.

You also mentioned that you where using an adhesion promoter, that's great as well, could you tell me what kind, brand name, etc. If I've used it, I may have more information or tips that might help. They are all fairly similar but just in case I have used it.

I would be more than happy to go over your plan of attack with you...just throw it up and we will see how it goes...It's almost like a test in school and the posts are cheat sheets...LOL

All the best

Ray
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Old 08-13-2013, 02:02 PM
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Okay, I just reread your posts again and you did say that these are practice panels and you weren't that concerned about primer. I'll wait for your plan of attack post and we will address more then.

Thanks
Ray
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