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Old 10-09-2003, 09:19 AM
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Orange Peel and baking

Hello All I am new to this Hot Rod board but I have been painting for about 3 years, I mostly do small stuff, RC model airplanes (2 Meter class) bumpers, hoods, etc... I use PPG K36 primer DBU paint and ppg DCU 2021 clear. I shoot most every thing with a Harbor Freight HVLP gun. The problem I am having is when I shoot my clear I get a bit of orange peel effect. It is not overly bad but I would like to get it better. I have heard about baking paint for better finish results. I shoot on the pourch of my shop with plastic sheeting closeing every thing in. I wonder if after I get done shooting my clear if I waited 10-15 min for the gas and over spray to get sucked out I could turn on a heater to raise the temp in that area to warm up the paint to reduce the orange peel efect? Any suggections? Right now I am shooting a bumper for a maxima, I painted cleared and was wet sanding the peel out, and went through the clear in to the paint and have a faded spot.
so I need to redo it, I just don't want to have to sand as much this time.

any help out there.
Thanks guys...


Fozzyber

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Old 10-09-2003, 11:05 AM
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I see you live in south Lousiana where the temp and humidity are fairly high. I live in southeast Texas. Use the DT895 reducer for high heat conditions. I just sprayed some DCU2002 cear with my HF HVLP gun. I thinned the clear 150% as opposed to the recommended 100%. The clear layed down like glass and has absolutely zero orange peel. The clear must be applied in wet coats. If it is not, a non smooth finish is guaranteed.

Vince
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Old 10-09-2003, 11:10 AM
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In my experience- the reason you get orange peel is because the paint is going on too dry. It could be that you are too far away or the paint is too thick or not mixed well. Make sure to thoroughly mix as per directions and give a full wet coat as your last when you clear. When the shop is around 70 degrees I think it is optimal, as if it is too cold OR too hot you have the risk of peel. Good Luck! Try different gun settings and spraying a little closer to the work and see if it helps!
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Old 10-15-2003, 09:11 PM
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I have used a lot of 2021 and I have found that when I spray it at work in a down draft booth it looks great and I can use it in my shop and I have the same problem my guess is the amount of air that the down draft has compared to my booth??
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Old 10-15-2003, 09:28 PM
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i double the size of exhaust in my homemade booth & found my clear layed down better. like a metallic i just pour paint on to get wet build up for adhesion & 3 rd coat is 10% overreduced & i don't use my buffer much. the other thing is i went from 6 flourescent lite to 14 with some spaced down walls. having painted in alot different environments i think watching your puddle wether it welding or painting is most important thing. youmentally adjust your gun handling or walking speed if you watch it hit & build on panel jwart
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Old 10-15-2003, 10:26 PM
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What air pressure are you shooting? I've found PPG 2021 needs about 50-55 psi *at the cap* which means about 55-60 at the guage... 2021 will lay out really slick and smooth for me at that air pressure.

Temp has to be at 70 or above and the catalyst won't "cure" properly if the temp is not at least 70 for 12 hours after you shoot.

Baking it will help the cure time, but won't fix the orange peel issue -- that's an atomization problem. Also, how close are you holding the tip the the item being sprayed? you need to be about 4-6 inches away max.

Good luck,
JP
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Old 10-16-2003, 09:15 AM
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Orange Peel and baking

I am holding the gun close to the 4-6" maybe 7" but close.
I just thought maybe the heat of baking changed the flow of the clear on the hood, making it run and thin like powder coating is this true? Or when is is on it is on and what you shoot is what you get? I do find I get less orange peel when I shoot DC3000
The "new" ppg fast drying clear, maybe I just need to shoot it instead....
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Old 10-16-2003, 09:49 AM
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Yeah, since Urethane Clear uses a catalytic reaction to set and not air, baking will not cause it to "flow out" better.

I've used the 2021, 2042 and 2082 PPG clears and I've found them to all lay out about the same, I would not expect the 3000 to spray much different.

All the clears are really sensitive to the amount of catalyst mixed in them -- make sure you are really accurate in the amount added to the clear.

I would suggest taking a piece of cardboard or wood for testing flowout and spray some clear with several different air pressures and distance from the panel. When I spray 2021 on a panel, it goes on fairly slick and actually "flows out" in a minute or two after I spray it and gets even slicker. I use a Sharpe Platinum gun with a 1.3mm tip and 55 psi at the cap and I spray about a max of 6" from a panel.

Here's a link from PPG with more info on what causes orange peel:

PPG Orange Peel problem resolution

The *good* part about orange peel in clear is you can sand and buff it out (as long as you have enough coats), but of course, that's a lot more work! I usually can get it slick enough where I can go straight to 1500 grit sandpaper and then to the polishing steps.... a lot of bodyshops would not even do that!

Good luck!

JP

Oh, one more thing Fozz... I just re-read this thread and saw your first part about using the Harbor Freight HVLP....

First of all, I think it's a pretty good gun for the money, but it doesn't spray nearly as nice as my $300 Sharpe (ya think?) and I use the HF gun mostly for touch ups or when I am doing multiple colors... clear is a lot touchier to spray than basecoat.

But... there is no reason you should not get a great paint job with that little HF gun, you just need to work with it a bit to get it set up properly.

First -- that air guage HF provides with that gun is woefully inaccurate; mine reads about 10 psi low! That could certainly cause orange peel.

Second -- On my gun I have to barely crack the air mixture setting and I have the fluid cranked down almost wide open.... yours may be different... Also, the little knob to adjust fan size is basically wide open on mine. I found the HF gun to be a little "touchy" about these settings -- experiment a bit...

Here's hoping your next clear job is SLICK and CLEAN!!!

JP

Last edited by johnspierce; 10-16-2003 at 09:49 AM.
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Old 10-16-2003, 07:27 PM
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JP.... I'm sure that you will not get many arguements about getting better results from a high dollar paint gun. The fact is, most people don't have the money or need for one. With the proper settings, you can get acceptable results from something considerably cheaper. It just takes some guidance or practice.
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Old 10-16-2003, 08:46 PM
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I'm certainly not suggesting that Fozz get a different gun -- I just wanted to point out that the Harbor Freight gun I have is a bit touchy to adjust; it will still do a fine job.

Also, I am just suspecting that Fozz's problem might be too low air pressure at the gun - that is a very common reason for orange peel and as I said, my Harbor Freight gauge supplied with the gun reads 10 psi low.

The Harbor Freight guns offer a very good value for the money. Happy spraying!

JP
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Old 10-17-2003, 08:33 AM
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Yes I would like to get a better gun as && allows but right know it is the HF gun. I shot some K-36 last night and I did a few things different, I added a few more lights, and cranked up my fluid flow.
so that I was flowing a full wet coat with one pass. This helped so much. I was almost getting a sand free surface. I am going to try the same thing with my clear. Ill let you know what happens

Fozzyber
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Old 10-17-2003, 01:38 PM
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Sounds like you are getting ready to experience that nice slick clear coat! I know the HF gun can do it -- I've sprayed PPG clear on motorcycles several times with it.

JP
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Old 10-19-2003, 07:09 PM
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Cool PAINTING

I HAVE HEARD IT ALLSOME I DONT BELIVEE THIN THE CLEAR ABOUT 10% MORE UP THE AIR PRESUREABOUT 70PSI STAY 10-12 INC FROM WHAT EVER YOU ARE SPRAYING PUT ON TACK COAT. LET IT CATCH PUT TWO COATS OF CLEAR WET. WALK AWAY IT SHOULD BE FINE ME I WON ABOUT 40 SHOWS BEST OF PAINT PLEANTY TIMES WORK EASY IT WILL COME OUT FINE WHEN YOU WET SAND PUT LIQ SOAP IN THE WATER IT WILL SAND BETTER AND THE PARER WILL GO TWO TIMES AS FOR SEEYA
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Old 11-24-2006, 06:55 AM
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Hello,
This is my first post.... but I want to ask if the HF gun you are talking about is that purple one...I am using the same with DCU 2082 Stratoclear w/2083 activator....I have ran out of the 2084 and and ran to the paint store to get a refill but all they had was 2083. I experienced what PPG tech suport called a "solvent pop"...the clear intially looked great (with the 2084) (sometimes the gun would sputter the clear....Is this a setting on the gun?) but when I got back from the paint store (about an hour later) and remixed with the 2082 with the 2083 the clear turned to a "cloudy" look... is this what they mean by a solvent pop?

I thought I would let the clear dry and sand, up to 1200 (wetsand) when I buffed with Meguiar's Yellow 8" pad with Meguiar's 85 high cut compound, I noticed the base coat had spots in it,Clear buffed realy nice,,my base color is black...I tried sanding this out but it looks like these spots are showing up in the clear...I took the sanding down almost past the color coat and the spots are gone...so my guess is that these white spots may be a result of the compound working in the solvent pops???? Anyone experience the same????

I am going to re-shoot the base and reclear today...rare day up here in Chicago...60 degrees after Thanksgiving...ya know?
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Old 11-24-2006, 09:45 AM
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There's a couple of different things that can cause solvent pop. Spraying your clear coats too close together, spraying the clear too heavy, using the wrong temperature activator. Also, I've sprayed a lot of PPG clears and HOK clears and can say without hesitation that PPG clears solvent pop easier.

On a day where it is only 60 degrees out, you are actually shooting on metal which more than likely is 50 degrees or less, which is below the margins PPG recommends for shooting. If you don't have some heavy duty heaters to warm the metal up, you might be looking for trouble. If you are doing a whole car, this is gonna be a problem. If you are doing just a fender or hood or motorcycle parts, one of the things I have done in the past is use an industrial heat gun to heat up the metal before I shoot.

I know a lot of folks don't like to mix products, but I have shot HOK clears over PPG and Dupont for years with no problems at all. The HOK shoot much easier and is more forgiving of temperature. I haven't noticed any difference with final sheen or durability.

You have done the right thing by sanding down till the pops disappear. Those are nasty little boogers and will come back through your finish if you don't go almost all the way to the base coat.

Try shooting lighter clear coats with a longer time between coats. On a cool day it's probably safer to shoot the coats a little less "glossy", which of course will require more sanding and buffing, but will have much less chance of solvent pop.

good luck,
JP
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