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KNanthrup 07-08-2006 08:40 PM

Help! Newbie first paintjob, acrylic enamel issues
 
2 Attachment(s)
Ok so I'm doing my first paintjob on an '84 S-10 before I head off to college. It's a budget job but I want it to look decent.

I stripped it down to metal and did a bit of body work, then coated it with urethane 2k primer and then I worked the primer surface down to a 600 grit surface.

Then I decided to do some test shooting on my fiberglass rollpan to get a feel for what the paint is going to do. Same prep work on the rollpan. The paint is PPG Acrylic Enamel in gloss black color.

SO, I go to and shoot it on and the thing is just a straight orange peel mess. Is it normal to be so uneven on the first shoot? I have never shot auto paint before so I had NO idea what to expect but I thought it was supposed to shoot on smoothe. It's very uniform of orange peel (high/low spots) it's not a reaction or anything from the surface.

Then I have been reading about final detail work of painting involving polishing or wet-sanding from 1000-2000grit sandpaper after the paint is cured. But is this for other types of paints or does it work for acrylic enamel? Are my results normal and smooth-able from final detailing or is something wrong somewhere?



Here are pics. The one looks worse for some reason, might have been my mistake on the coating. The other one I hit the coat pretty heavy.

kenseth17 07-08-2006 09:30 PM

wow, ya, there is a bit of peel there. I think you have to play around with your gun adjustments. What air pressure did you shoot at? Also did you reduce the paint correctly if it called for it. So many factors can cause orange peel from your gun adjustment, pressure and fluid, paint viscosity, how far you are from the surface, ect. Or even the proper tip and aircap in the gun you are using. Could also be too fast a solvent or hardener not giving proper flow. Hard to say what the cause is in your case. Good thing you practiced before doing the car, smart man. Keep playing around with your gun settings and distance, speed and pressure and get it shooting better and be set up before you start on the car itself. Then only minor adjustments may be needed. As far as wetsanding and buffing orange peel in an acrylic enamel, if a solid color and a hardener was added, it normally can be, If not then its pretty much what you spray is what you got without clear on top. Even if cleared you would want it smoother then that. I think its repaint, that looks like quite a bit of orange peel to sand and buff out. Heres a link to orange peel and causes. Good luck on try 2.
http://www.ppg.com/PDSmaxmeyer/Selec...e=44&CurrSel=3

KNanthrup 07-08-2006 10:02 PM

Hey thanks for the reply. I'm working with the gun a little trying to figure out what's going on. It's pretty frustrating the way its going so far. One thing I did start to figure out was that I'm using 3/8 hose and something like 25' of it so I realized I probably needed to crank the pressure up more. See the thing is I am only regulating pressure out of the tank, my gun does not have a gauge on it. The gun is supposed to shoot between 2-3.5bar at the handle and I had it set at 3bar out of the tank. I turned it up to 4 out of the tank but I am not sure with 3/8 hose and 25' where that puts me at the gun. Can't imagine quite how much pressure I would lose along the way?

The other thing is it doesnt seem to come out with a very good gloss to it. Not a fresh paintjob kind of shine at all. Is this part of the buffing and polishing stage? Will a new coat of paint be a little dull when it's first sprayed?

I know that the reducer and the hardener are correct for the application because I have the spec sheets on the paint and they were matched by the body shop.

Right now I am really going to have to figure out how to fix this orange peel. As for my failed paint... can I just wait for it's designated dry time (16 hours) and then sand it off, or rescuff and 600grit it and respray?

kenseth17 07-08-2006 11:14 PM

Acrylic enamel should spray glossy and remain glossy (unless a flattener were added to make it a semigloss or flat paint) It should add a little gloss with hardener added vs no hardener. You really should have a regulator at the gun. Run the pressure full on the tank guage, and after 25' or more of airline should be a moisture trap, and then regulate to spraying pressure at the gun. 3/8 airline should be fine with most conventional guns, but many hvlps need high flow fittings to spray right. Just make sure you are not losing too much airflow anywhere to the gun, like nothing restricting it. I am guessing maybe your pressure was too low at the gun if you have no idea what it is and the correct hardener used and right viscosity of the paint. Pick up a regulator to install at the gun. If your using a conventional gun your pressure should be somewhat high, probably somewhere around 50 psi at the gun, but start at paint man. recommendations and adjust from there till it sprays well. What it boils down to is the paint isn't atomizing. You want it to produce fine enough droplets that the surface with be smooth but not dry. You control this by tip selection, fluid flow, as well air pressure and your distance and speed spraying. Read some of brian martins (martinsr) basic of basics on gun adjustment, should be on this site if you do a search, as well as some other threads. Also southernpolyurethanes has an article on gun adjustment I believe. Most conventional guns the needle size in them should spray enamel okay. Any idea of the tip size you have and what gun are you using?

swvalcon 07-08-2006 11:20 PM

thats where you can see the pros from the beginners. Not as easy as the old timer made it look is it. My guess is you need to practice with gun settings and spray techniques as well as mixture.

kenseth17 07-08-2006 11:22 PM

ohh missed the second part. Yeah if you can get it to sand smooth with 600, sand it and repaint. Acrylic enamel is a pretty slow curing paint. Try after your 16hrs. Good thing you added hardener, or the cure time would have been forever and a year. If it is still gummy and wants to clog the sandpaper, set it in the sun for awhile, that should help the cure.

KNanthrup 07-09-2006 01:06 PM

Quote:

Originally Posted by kenseth17
Acrylic enamel should spray glossy and remain glossy (unless a flattener were added to make it a semigloss or flat paint) It should add a little gloss with hardener added vs no hardener. You really should have a regulator at the gun. Run the pressure full on the tank guage, and after 25' or more of airline should be a moisture trap, and then regulate to spraying pressure at the gun. 3/8 airline should be fine with most conventional guns, but many hvlps need high flow fittings to spray right. Just make sure you are not losing too much airflow anywhere to the gun, like nothing restricting it. I am guessing maybe your pressure was too low at the gun if you have no idea what it is and the correct hardener used and right viscosity of the paint. Pick up a regulator to install at the gun. If your using a conventional gun your pressure should be somewhat high, probably somewhere around 50 psi at the gun, but start at paint man. recommendations and adjust from there till it sprays well. What it boils down to is the paint isn't atomizing. You want it to produce fine enough droplets that the surface with be smooth but not dry. You control this by tip selection, fluid flow, as well air pressure and your distance and speed spraying. Read some of brian martins (martinsr) basic of basics on gun adjustment, should be on this site if you do a search, as well as some other threads. Also southernpolyurethanes has an article on gun adjustment I believe. Most conventional guns the needle size in them should spray enamel okay. Any idea of the tip size you have and what gun are you using?


Thanks so much for your help. I am using an HVLP gravity feed gun. The tip is a 1.4mm, but I don't really know what that number means in terms of what it does to the paint and if it is correct for what i am doing. I guess i should get a regulator at the gun but it's Sunday and everything is closed, so I may do a little more experimenting. I don't know how much air pressure loss would occur through my line but i think i might try turning it up even a little more. Any idea what happens if I go past the max amount for the gun?

I don't know, I guess it's my fault for lack of equipment and technique prep but it's just been very frustrating for me to come to such a basic vital problem after 50+ hours of body work and prep and I can't even get a basic coat on paint shot. Ahhh!

KNanthrup 07-09-2006 01:43 PM

I take that back. The gun I'm using is the cheapy Zhipp H827W marked on the bottom. It's advertised as an HVLP on the box but from the reading ive been doing on this forum it sounds like it may not be HVLP after all? It's not marked HVLP on the body. The only strange thing is the box model number is H827-B and the gun is marked H827W. Don't know if that means anything or not.

Regardless of HVLP I hope I can still get this gun tuned to shoot a decent coat. I'm thinking maybe I need to crank that air pressure up especially if this thing is not HVLP after all. I just don't want to ruin the gun.

kenseth17 07-09-2006 04:48 PM

Yeah I would try turning up the pressure a little. You really should get a regulator for the gun though. After experience you will sort of be able to guage your pressure without even looking at the guage, but you still want to be able to regulate it at the gun. They are not totally accurate, but should give you an idea where you are at. Yeah I have a zhipp gun, different model, and it is advertised as hvlp, but really isn't an hvlp gun. I think I shot around 50 p.s.i with my gun on the last coat of urethane clear and it shot well. but you have to find your own setting, different gun, urethane paint. Mine layed out well for me.
I think you should be able to spray enamel with a 1.4 tip. Been many years since I've sprayed enamel, and it was mostly conventional guns with around a 1.6 tip, binks 7, devilbiss, ect. If airpressure doesn't improve things, you may try over reduceing it a little to get it to spray better, or if it doesn't call for reducer, buy a decent grade of enamel reducer and add it in and see if your results improve, probably medium or slow reducer depending on temps. I wouldn't overreduce much more then 10% though. Most hvlp guns still call for fairly high pressure going into the gun to spray well, the gun itself reduces the pressure inside to give complient pressure at the aircap. But there is such a wide range of pressures people set there gun at depending on what they have. I've read some say as little as 23 pounds inlet pressure on here, My accuspray hvlp I set somewhere around 40-50 lbs inlet. There is usually a max air pressure rating on the gun body, or should be in the manual inside the box. If you over pressurize too much, not sure what would happen. I think mainly would blow out seals.

KNanthrup 07-09-2006 07:57 PM

Kenseth, you have been such a big help so far thank you for your patience.


I did a little more experimenting today and seem to be making a little progress. It seems to be shooting a little smoother with the air pressure up and I have been over-reducing it as well.

I guess maybe I just don't know what phases should look like what. On the spec sheet it says recommended 3 coats and each coat can be shot after 5-10 minutes of drying time. Now, my issue is that I guess I really don't know what each coat should look like.

I'm starting to realize that it doesn't really get a good glossy smoothish texture until you get a real thick layering of it on there. Maybe I just need to get 3 good solid coats on there before it will smoothe out? Shoot I shoot a rough base coat then 2nd coat kind of medium then 3rd on to smoothe it out, or do I lay thick coats every time?

I'm such a newbie to this.

The other issue is I seem to be getting overspray dust on other parts of the hood while I am working across it and I think this is severly affecting when I get to that part. When I look at the hood in the light, it just doesn't look uniform throughout, it looks rough in some spots and smoother in others.

I will take some pics in a bit after it dries for a little visual to go by.

kenseth17 07-09-2006 09:22 PM

maybe overspray landing on the surface is causing some of the roughness. What do you got for ventilation? I had a problem with that years ago when I was only using a house fan for ventilation. Doesn't move much air. But I was using basecoat so it was real easy to tack off the parts before putting on paint, since it drys so fast. Acrylic enamel singlestage your really can't tack between coats. Painting with highpressure and conventional guns, it would really get cloudy inside the garage not to mention not too healthy to be painting in (any activated paint is really bad if you are breathing it in, or its absorbing through your skin, eyes, ect) Its real easy to have a mask that has enough gaps between it in your face that you are getting exposure through that and your skin, ect. I don't know what to suggest as far as what to do about the overspray problem you are having other then to get better air movement. Also remember you need a place to take in fresh intake air opposite of your exhaust to get airflow and fresh air.
You may have to find a pattern around the car that will minimize your overspray problem. Maybe start nearest your exhaust on the first coat and painting into the airflow, and hopefully the overspray will melt in and won't be painting over rough overspray landing before you get on the first coat, and hopefully following coats it will melt in. Everyone has thier own pattern around the car and I use the same one as when I started, but overspray really isn't a problem for me anymore since I got a pretty good fan now, and have a window I can filter incoming air through on the other side of the garage. A slow activator or reducer may help with the overspray problem some by leaving the top open and wet longer. Just be carefull not to run it if its way below the temp it calls for and leave enough time between coats. You could also try hanging parts like the hood to help prevent overspray from settling on it and get it out of the stream, if you have the room. The most overspray is going to settle on the flat panels. I don't know what to suggest, maybe start another topic on avoiding overspray if no one visits this thread and has an answer for you. As far as how I spray, I normally spray a medium wet coat on my first coat with singlestage or clear. I don't worry a real lot if it isn't perfectly glossy and has a dry spot or two. The first coat I just figure as a coat for the others to stick to, and want to avoid getting runs. But still want it wet enough and free of orange peel and being rough, or you will have to try to bury it with the following coats, and that will fight you getting a nice finish. The last two I spray wetter and want it wet enough so its smooth and glossy, and on the last coat I look down and over the panel closely while painting to make sure there are no dry or missed areas and is smooth and glossy as possible without running all over the place. The last coat you want the best finish possible to cut down on the wetsanding and buffing you have to do, or in the case of singlestage metallics and pearls, as good as possible cause what you spray is what you got. Everyone has different ways of spraying. Some spray a full wet coat on all coats, Have to find what works for you. As far as time between coats, I use the times in the tech sheet as a guide, but generally wait longer if possible between coats to lessen the chance of trapping solvent or building up coats too close together. You can feel a papered off area after your first coat, and when you touch it with you finger and its tacky but not wet, (paint strings a little) your ready for another coat. This doesn't really apply to basecoat since it drys so quick, but is a guage for singlestages and clear. Sounds like you are making a little progress anyways. Hang in there you will get it eventually. Thanks to Barry K from this board, I learned black and dark colors are the slowest to dry and flash off solvents, so don't cut short your flash times. I always wondered why back when I used to have a little problem with solvent pop it was usually a black car. This forum is great, even if you have been painting for awhile can pick up things you never knew. Good luck.

KNanthrup 07-09-2006 09:32 PM

Ok that's great info. I barely have any sort of air movement so I guess that is one thing I completely forgot about and need to work on for overspray.

As far as the finish goes, I think one of the issues I'm having is what you described as "dry spots" where the surface does not look uniform in the light in some areas. A lot of the non-uniform look seems to be coming from when I lay a new pattern above or below one that I already shot. For example, I lay a line across then move up and parallel back the opposite way, and at the small point where they are overlapping, it seems to distort and come out rough. Is this a sign of something going wrong? I did the front of the hood where it's only thick enough to lay out one line across it and it seems to have come out fairly good without the affect of another line pattern near it.

46chevyfleetline 07-09-2006 09:41 PM

This time of year I will use a slow reducer and wet look hardener. I always lay each coat down as I want it to look. Just a bit of practise and you'll do just fine. You've rec'd some great help in the previous posts. Cheers!!!

kenseth17 07-09-2006 09:45 PM

May be your spray technique. Keep the gun parallel to the surface. Start moving the gun, pull the trigger, make as long of a stroke as you can keeping parallel, release trigger, follow through stroke, overlap the previous coat 50-75 percent with your next pass in the opposite direction you sprayed the first time, doing the whole starting to move the gun before pulling the trigger, keeping parallel, realeasing trigger before stopping your stroke thing. Just takes some practice to get the hang of. If you notice dry areas while painting him them areas with more paint while still wet. The dry streaks could be not keeping the gun parallel or overlapping enough. Also slow activator like fleet said will give you more time to get around and get it looking good.

46chevyfleetline 07-09-2006 09:53 PM

One other thing. If you are exhausting from the side of the car always start painting on the opposite side you are exhausting from and paint towards the fan. That way you are not pulling overspray over freshly painted areas. JMO of course. Cheers!!


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