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Old 02-01-2005, 01:28 AM
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Unhappy Painting and Clear with PPG, what do I do next??????

OK, I have shot the base coats on my car, PPG Dodge Viper Blue Pearl Metallic and Ford Utica White stripes; the clear has also been applied.

This is my first ever attempt and up to the clear everything went well. The Clear is the most difficult part so far, here are the problems.

I mixed the clear 1:1 and sprayed the whole car. I tried to keep the same distance, angle and speed overall but got smooth, rough and gritty areas. (surface prep was perfect) I sanded with 600 after 3 to 4 days, 1000 or 1500 would not cut the finish easily. Some areas were smooth, some had the little shiney dots which I could not get rid of without cutting throught to the silver and some areas I just ended up cutting through to primer..

I am going back to spot the bad areas with base and re-clear.

My questions are the following:

1. can I spot the areas I broke through or do I have to repaint the whole panel. In some cases I cut the clear and the top of the base to the silver, others I hit primer.

2. For the clear, after the pattern and gun are set per martinsr's guide, what finish am I going for wet, thick, thin or other?

3. How many coats of clear and how long before reapplication?


Thanks in advance,

Jim

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Old 02-01-2005, 06:31 AM
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You'll need to "dust" in and blend the base color and then recoat each entire panel with clear. Are you using DBU or DBC?
Ahh, is the clear DCD35? with Dfx=11?

It would help to know exactly what are you using however either could be recoated after 48 hours (to be safe) and 2 wet coats of clear (2 passes =1 coat) would be enough this next time around. If you don't spray that often the faster or Supercharger DFX-11 Clear hardner wolud be best way to avoid sags even if you get a little orange peel to buff out later in the trade off.
hope to have helped. .
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Old 02-01-2005, 06:36 AM
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#1 You can spot these places with base but I generally re-clear the whole panel. #2 Thin coats and keep it slightly wet between coats. If you keep the coats light by the time you finish a coat it should be right to start your next coat. #3 I usually go with 3 or 4 light coats and then go back over the leading edges of the front because it takes so much more abuse, and on the body lines and panel edges because you will rub through there first. Keep it clean and good luck Dave
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Old 02-01-2005, 08:23 AM
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All I can say is I don't think speeding up your clear is going to help, it will hurt. You are getting "rough" spots, that sound like dryness from clear that had flashed off and the overspray wasn't re-wetting and laying on top. You have to have some pretty sever temp vs solvent speed with urethane clear to get this condition so I would look at those first.

Was the solvent (reducer) "temp" matched to the temp in the shop? How about the hardener "temp"? What clear is it, don't know of any PPG that is mixed 1:1 (but I admit there is a lot about PPG products I don't know).

Look at your overlap and start and stop points as you spray. You may be coming to a panel too long of time after it was shot and the clear has started to kick before you get there.

DO FOLLOW Mighty mouses advice on the recoat. Apply LIGHT coats of base over those sanded thru areas. Then after you have built up a little "shell" over them, let it flash GOOD before applying the clear. Agian, apply the clear with caution as well. If you apply it too wet the solvents can get under the edge of that sand thru and lift it.
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Old 02-01-2005, 11:38 AM
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Your "dot's" are probably "craters", That's why you sanded thru to the base. Those could be lot's of things.Trash,water,solvent.(undisolved pearl Don't ask) I seem to be plagued with them myself some day's.I went back to using the little filter that goes into the gun between it and the cup which has helped. It's amazing how much crap get's into the cup after you've strained the clear. It's like a dust magnet some day's.
Something that helps me lay clear is to use a stand mounted light which I position at one end so's I can sight down the panel with me ahead of the gun and "see" the material as I'm spraying it. That helps to eliminate "thin spots" as well as thick one's.If you get what I'm saying.
As said,You'll need to clear the whole repair panel as blending clear into existing for a spot repair is difficult at best.
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Old 02-01-2005, 02:25 PM
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More questions

Wow, you guys are incredible and fast on the response. Thank you very much for the assistance. I have discovered a couple of other things I did.

The Clear is DCU 2010 with DCX 2012 hardner. I don't know where I got the 1:1 from but I actually used 2:1. The data sheet says 4:1. So I will make that change first. The data sheet mentions two passes equaling one coat. Does this mean making two passes. one on top of the other and moving down and two passes and so on?

The shiny dots I mentioned are not due to contamination but are the results of not knocking off the high areas and leaving valleys in the clear. As I mentioned some panels were excessively rough, heavy orange peel.

Additional questions:

1. I was told that with this clear I should use a higher gun pressure of 14 instead of 10? Is this OK?

2. While I am spraying the clear is a distance of 8" OK? I think I was half that before.

3. Originally I used 600 wet/dry to sand, this time I would like to use the 1000, 1200, 2000 grits, do I need to have a large quantity of these? I tend to use sand paper until I am polishing with it before I start a new piece.

4. What about corners, edges and high areas, I noticed they also need a little cleaning up? How do I do this?

Thanks again,

Jim
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Old 02-01-2005, 09:17 PM
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If you've got numerous cutt throughs on all the panels I would recomend you tape off the stripes and dust the whole car with a few light coats of color then reclear it completely with the right mixture of hardener and clear. If you mixed a 4-1 product at 2-1 the dry time will be different and also the spray characterisitics of the clear. I'm sure with the clear mixed right the stuff will spray a lot better the second time around. I't impossible to give you an idea on spray gun settings not knowing what gun, compressor, hose, etc you have. There are too many variables. adjust your gun and shoot on a test panel before using it on the car, also make sure your compressor is adequate for the job- if it can't keep up and volume and pressure drops off the paint will not be atomized and will turn out rough and orange peely like you described. Bob
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Old 02-01-2005, 10:51 PM
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Jim, one thing I noticed in your response was the "1. I was told that with this clear I should use a higher gun pressure of 14 instead of 10? Is this OK?"

You really need to find out what the MAXIMUM INLET PRESURE IS. What kind of gun? 23-50 lbs is common depending on the gun. If are setting that gun up at 14, HOLY CRAP are you going to get some serious orange peel. That is WAY, WAY too low for proper atomization.

10 lbs AT THE CAP IS ONLY FOR LEGAL REASONS!
I am not yelling at you, I am yelling at the manufactures. Every darn spraygun mentions this 10 lbs at the cap, it is NONE of your concern and they should explain it!!!
10lbs at the cap is for LEGAL reasons. To be a "Legal" "compliant" or in some places an "HVLP" (Compliant and HVLP are one in the same some places and not in others) the gun can not have more than 10 lbs at the cap. In other words that 10lbs at the cap only means that is the max to which it can take before it looses its "trasfer efficiency" that is required by law. This "transfer efficiency" is 68% in most places as I remember. So, if you were to go above that 10 lbs at the cap, in other words if you were to put more than the MAX pressure that is stamped on the gun (or in the instructions) that is recommended by the manufacture your "Transfer efficiency" will go down. Less of the paint sprayed out of the gun would stay on the panel being painted and more would end up as over spray, THAT is what they want to stop.
SO, that 10 lbs means NOTHING to you, you don't even have a way to measure it. It requires a special air cap with a gauge on it that costs about $150.00. The "INLET" pressure is what you should be concerned with. That is the pressure AT THE GUN. NOT at the wall at the begining of the hose but AT THE GUN at the end of the hose where it hooks to your gun.
In fact, if you shoot the gun at the max inlet pressure (it is required to have this MAX pressure stamped on the gun here in CA.) the manufacture has made the gun so that it is impossible to go over that 10 lbs at the cap. THAT, is why they have the MAX pressure stamped on the gun.
I can tell you this, with the inefficient air supplies that most of us home hobbyests have you will not even hit the 10 lbs with the gun inlet at MAX.
So if you were to set the inlet pressure at a few pounds OVER the MAX that is recommended by the manufacture, you will get better atomization and you will STILL be under the 10 lbs. Your gun "should" operate at it's best at this 10 lbs at the cap. But being you don't know how much you really have at the cap, you will never know. You can bet this though, 11 lbs at the cap is a heck of a lot better than 9lbs at the cap for your painting quality. So, if you were to bump it up a few more pounds you will atomize a little better which is a good thing. I have a test cap, I have used it at many shops and found very few would give you 10 lbs at the cap when the gun was set at the recommended MAX setting. This is because the VOLUME of air that the gun needs to accomplish the 10lbs at the cap is not found at many shops and sure not at home garages. You may have the lbs but not the VOLUME, they are two different things.
Brian
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Old 02-02-2005, 03:00 AM
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The original mixture of clear I used was 2:1 but I found out today the spec sheet says 4:1.

I have a Central Pneumatic Professional Gravity Feed gun from Harbor Freight Tools. There are no markings on the gun showing pressures. It does have an inline regulator at the inlet which two scales 0-12 and 0-160. Which scale should I be using? There are three adjustment knobs on the gun; one at the base of the handle by the inlet which is the air adjustment, another at the back of the gun the fluid control and a third on the side called a control knob.

Until just now I have been using the control knob and the fluid control knob. I just realized the control knob is not the air adjustment.

This along with the improper mix ratios really sets me back.

I have a 60 gal compressor and the line pressure is around 90-120. I have a regulater at the inlet of the gun and it was set at 10. This is the one I meant by at the tip. I misunderstood which end you were referring to. The pressure at the inlet is the one I wanted to adjust to 14.

Any ideas on the sanding issues I mentioned?

All I can say is HELP........
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Old 02-02-2005, 07:52 AM
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Jim, let's get on the same page on a few things. First, that guage, I am a little glassy eyed this morning with my cat keeping my up much of the night. I don't have the foggyest idea what that guage could be reading with the two levels.

That gun is a SATA NR95 copy as far as I know, it should be set at 23 lbs AT THE GUN. So if you have a regulator with a guage at the gun it should be set at 23 (geeez, I think it is 23, let's see 23 for that one and 29 for a Devilbiss GTI.........I think that is right). That dual zone regulator may be saying at X lbs on the big scale it is Y pounds at the cap on the small scale. If that is the case, the 14 you had meant the high scale was at 30 or something. That makes sense. But if that was the case, you may have been too high. This would make sense with my first post, and that you have a too fast of flashing issue. This and improper overlap left you dry spots.

Second, do you have a full understanding of the mixing ratio? 2:1 and 4:1 is a heck of a difference. 4:1 means four equal parts of clear to one part equal to on of the four of clear in hardener. Four tablespoons clear to one tablespoon hardener or four pints clear to one pint hardener or four gallons clear to one gallon hardener, they are all the same.

Are you saying you mixed two parts clear to one part hardener? So if you mixed up a gallon of clear you used two quarts hardener? If this is the case you have twice the cowboys for horses guy. It is not going o be insoluable as it did not fully cure.


I know one thing, I don't think it is a surprise to you that I think you got in over your head. I HIGHLY recommend you get a scrap fender or two from a body shop and spray them to till you get a feel of it before you jump back to your complete.
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Old 02-02-2005, 09:26 AM
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I HAD a page full typed last night but my POS computer locked up before I could post it.So I went to bed PO'd.

I believe the 2 scales your referring to are Standard and Metric.

I have the "purple" HVLP gun from Harbor (nice gun for the $$$)
It has a "green" area of proper working PSI and as long as your in that zone your close.
It has an air adj. at the bottom of the handle which I leave wide open unless I'm shooting small parts or wanting a more direct pattern.

With a 3/8 25' hose, I run around 50-60 at the hose regulator and adjust it to the middle of the "green" area with the gun reg. I don't know exactly what PSI that is but I can look tonight and see if you want. The instructions with the gun should give you SOME idea of required max PSI or at least a range.

As for "How far away" do this, Open the FAN knob wide open and the fluid (the one on the top if your fan knob is on the side) half way open,usually 3 full turns out,hold the gun away around 8"and spray a test area. The idea here is to see how wide your fan pattern is and adjust the fluid to get good coverage.
The idea is this, Your distance from the panel is dictated by HOW WIDE THE FAN IS. If you have good coverage with an 8" fan,Paint 8" from car, 6" fan,6" from panel.All gun's have different fan's and you need to know what your gun will do best.You get the idea.
Some painters run everything wide open and paint like mad,Other's go less and slow, You need to PRACTICE and find what's best for YOU.

Find MARTINSR's post on "Atomization". If it's not here,It should be.

As for sanding.
That will be dictated by your finished work, As you know,starting with 600 will get it knocked down faster but you've seen the results of it. I will use 600 only for a color sand before the final clear coats and usually only if I have graphic's with several coats on them.
I start my finish color sanding of the final clear with 3M Hook-It II 1500 on an interface pad on the DA,DRY. That will give me an idea of how I'm progressing and adjust grit up or down depending on how well it's cutting. If it's 'peeled/trash bad,I'll start with 1000 and just let the weight of the DA cut but keep a CLOSE eye on how it's cutting.
Point being,You have to increase your grade of paper sequentially,so the coarser you start with the more steps you have to go thru to finish. I'm sure some start with 600 and go to 2000 but it will usually show after buffing.
If I want a super good finish,after 1500,I'll go to 2000 wet,Then go to a 3000 Tranzact pad,Perfect-It III Regular cut compound/wool buff,Swirl remover/black waffle pad.
Other wise I'll buff with 3M Perfect-It III extra cut compound after the 1500.Then swirl remover.
You want to sand & buff as soon as possible,usually 24 hr's, before the clear hardens.It's much easier and if you wait till the clear is hard,you'll be sanding your butt off.
I use a 3M detail cloth,the yellow one with the "ridges", for wiping the residue off which will build up quick dry sanding and will stop the cutting of the 1500. If you get sticky "ball's",stop and wait another day as the clear is still curing and will smear up your work.This is usually in cold weather/shop and shouldn't be a problem normally.
As for edges and such. Treat them as if there is a 0.0000001 layer of clear.Yeah I know,BUT,You get my point!!!
I hand sand,wet, with my old paper which doesen't cut as harsh, lightly, keeping close watch till it's close.Yeah,It's a PIA but it's worth the work later. Most times you can't see a little peel anyway so don't sweat some of it.
3M makes mini wool and waffle buff's which are VERY handy in tight spots. Well worth the $$$ for them.
As for how long a piece of paper will last,That depends on how your using it.Wet last longer obviously and a few drops of Ivory liquid in the water bucket will help with making the paper last longer as well as easier sanding. Soak your paper 15-30 min. ahead of sanding. This will help as well.
Sanding is an ART, and has to be learned from OJT and mistakes made.
Hope this helps some. Mike.

Lastly, Go find House of Kolor's Jon K's book's on custom painting.
It is a beginners/novice handbook with a wealth of down to earth info and "How to's"
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Old 02-02-2005, 11:31 PM
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Great help thanks....

Thanks again Martinsr and Bee4me, you have helped immensely.

To further clarify my previous posts; the pressure guage on the regulator on my gun has a single sweep needle but it is marked 0-12 and 0-160. The legend on the gauge says, 'Adj Range 0.5 - 8.5 kgf/cm2'. I have been using the 0-160 scale setting it to 10.

I understand that 2:1 is two parts material and one part reducer or hardener and 4:1 is four parts material to one part reducer or hardener.

Jim
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Old 02-02-2005, 11:46 PM
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Well, I have to admit, I have never looked at the "inside" numbers on a guage. I have been painting for 25 years and never paid attention to it. Instead of walking out to the garage I just looked at my Sharpe catalog and sure enough they are exactly as you say. Those smaller numbers are some metic measurement I guess, I have no idea what it is measuring.

All I know is the PSI on the outside is what you should be using. That "0.5 - 8.5" is one wild range, holy moly that is about 10 to 120 psi as I see it. I am sorry, I really don't know what to do with those numbers or what they mean. All I know is Sharpe doesn't even mention them, the "reads up to 160 psi" is all that is mentioned.

Anyway, find on the gun "maximum inlet pressure" or in your instructions. It should be somewhere in the 30 psi range like I said earlier. If you have that set at 10, you are NOT even coming close to atomizing that paint or clear. It is "falling" out of the gun onto the surface, not good.
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Old 02-03-2005, 04:35 AM
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You can put a little DT1870 reducer in the clear to help it flow through the gun as well. Not to much though , 5%

http://www.a2zautoforums.com/showthread.php?t=2792
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Old 02-03-2005, 07:31 AM
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That's fine, but let's start with the recommended mixing ratio and proper air pressure at the gun. After that some fine tuning with extra reducer "may" be needed.
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