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Two days ago I painted a car w/DCC-single stage acry urthane.
Today I masked the bottom half off & wet sanded w/600 grit & painted DBU over the DCC. Well I got some lifting of the DCC.. I thinned The DBU 100% w/885, temp was low 80's.
Is this a problem w/DBU.....Will using the base coat that has a reactive thinner eliminate this?
Don,
Probably not enough drying time before the recoat. Based on what the data sheet says, 72 hours or more would probably be better.
Also, I think sanding a 1-stage (which you need to do to overcoat) breaks the "skin" on the paint. I'm guessing that it should sit for a while after sanding also.
DBU is supposed to work over thoroughly dried OEM finishes.
Check the data sheets at the following website if you don't have them.
http://www.tricitypaint.com/docs.html
Sheets P-152 and P-168
DRR reducer is a pretty harsh reducer, and 2 days Air Dry of the DCC and cut open with 600 really let the DRR reducer penetrate the DCC therefore lifting.
May I ask why you reduced it 100%, DBU is mixed 50/50 I think with the extra reducer alowed deeper penetration.
1200/1500 grit would of been alright to sand with and it might not of let the reducer to penetrate so deep, and still allow good BITE of the DBU.
Lighter coats of DBU reduced 50/50 with 15 min. flash time between coats . most likely would of stopped the lifting.
Its not that you did it wrong, as any freshly painted product has the possability of lifting.
I have had DBU lift itself in the summer when 2 toning a truck. Paint can be a crazy animal at times.
Spray
I agree with spray, you over thinned just a little, and with fresh (2 day old ) single stage you may have painted too soon after cutting it. Single stage- even with a hardner- is not stable enough to even take wax for like 160 days after painting, so opening it up allowed deep penetration of your thinner.....I have gotten lucky by cutting it and letting it "breathe" for 72 hours, letting the vapors out, and then top- coating- but i was lucky. I have had it raise too.....a '67 cuda dash comes to mind just last summer, had to strip & re-shoot.
Henry had it dead on too........Good Luck!
Guys,
I'm guessing what Don said about thinning 100% meant the same as your 50/50 comment - that is, he put in as much thinner as paint.
You are right 100% reduction is 50/50. In the past I always let the paint bake in the hot Fl sun....but my back was hurting too bad to push the trk out of the garage. So I think everyone hit the nail on the head.....thanks.
speaking of DCC acryl urethane single stage, that is what I used to paint some of my panels that I'm done with.
I used epoxy primer first. Basically I am getting orange peel city.
After a little of that I tried sanding the primer perfectly smooth before topcoating with a 600 I believe, maybe a 400. Well that didn't work either, I'm still getting orange peel.
I think I got lucky on one fender and the top part that was sitting flat to the ground came out smooth as glass.
Does the position have anything to do with it, because it's basically impossible not to have some surfaces verticle.
How do you guys get paint to come out so smooth and nice?
Orange peel is caused by the painter, not the paint - and there are more than a couple of reasons. How do you avoid it?
1. Follow the paint data sheets religiously.
2. Do what it takes to get to the Met . . . practice, practice, practice.:D From PPG:
Quote:
Cause: Failure of the paint droplets to coalesce on the surface.
This may be due to:
a) Poor spraying technique, spray gun too far from surface, incorrect compressed air pressure, incorrect nozzle adjustment.
b) Excessively thick or thin film.
c) Paint incorrectly mixed, wrong viscosity, poor quality or incorrect thinner.
d) Insufficient drying time between coats, cold air fanning to speed drying.
e) Incorrect ambient or surface temperature, drafts.
Prevention
a) Use the correct spraying technique and ensure that equipment is correctly adjusted.
b) Apply paint in thin even coats.
c) Ensure that the paint is correctly mixed, use only recommended thinner with the correct grade.
d) Allow sufficient drying time between coats.
e) Spray within the recommended temperature range and ensure proper ventilation.
Remediatioin:
Rub out the orange peel, compound and polish. In severe cases it may be necessary to flat and repaint the surface.
Pretty much if your not controling the booth- then you can have a million reasons for Peal- the most comon is not enough flash time between coats, and nowhere enough flash time before clearing.
Follow the tech sheet as if it was the only thing between you & a good shoot.....well, it is - isn't it.
Also, are you shooting it on till it's nice & shiney when you apply it?
The flash time thing may have been the problem. I started waiting the recommended 15 minutes between coats. But one day I was talking to the guy in the paint shop and he said to spray a layer on a scrap piece before each coat and use your finger to test if it's ready for another. Basically he said when it sticks and makes little strings between your finger and the piece then it is good. that is what I started doing. The thing is, it would get like that long before 15 minutes. He told me if it got to the point where nothing stuck to your finger then it was too dry. I suppose maybe I should have been waiting longer.
Did it say anthing like this in the product data sheet? If not, you may have gotten some bad advice.Quote:
But one day I was talking to the guy in the paint shop and he said to spray a layer on a scrap piece before each coat and use your finger to test if it's ready for another.
Make sure the paint to reducer ratio is exactly what the data sheet says, and that it matches the temp conditions. Make sure your gun is set up correctly, with the right pressure, air and fluid adjustments. Make sure you're not laying down the paint too thick.
. . . . and practice on something you don't care about.
Thanks for all the replies. My Son was home this weekend & he said he put some left over silver base coat back in the can. So I when I used it I double reduced it.
Thanks for all the help.
Your welcome Don, if I helped.
tcodi- I tack between coats sometimes- if someone comes into the booth while i'm shooting, and I double the flash times before the first coat of clear, mainly when I shoot a tri-stage. The clear penatrates so much that I've had the basecoat shift under the second coat of clear off of a repair spot. Once bitten- twice shy.....also depending on humidity, you can adjust your mix some on your clear to help it flow by decreasing your solids by up to 15% max.
Get yourself a Viscosity cup & learn how to use it (no- it doesn't go on under anything before you paint). Good Luck...
I'm using a single stage so I didn't have a clearcoat.
The data sheet didn't say anything about the tackiness, it just
said 15 minutes, I listened to the paint guy though. Maybe I shouldn't have.
I definitely mixed it right, I was meticulous about that part.
The only other thing is, the data sheet says something like 8-10 psi at the cap, 40-50 at the gun.
my compressor has a regulator and I set it between 40 and 50. Is that right? What does "at the cap" mean then?
First, you should have a small regulator attached to the handle of your spray gun - right where the air hose attaches. If you regulate pressure at the compresor, you don't know what pressure you have at the gun because of the line loss in the air hose.
At the cap literally means inside the spray cap at the front of the gun where the paint and air mix. They make special gauges for that, but usually if you get the right pressure at the gun, the pressure at the cap will be close.
For instance, my Binks HVLP gives 10 PSIG at the cap with 18 PSIG at the gun.
What gun do you have, and is it HVLP?
On the bottom of the grip is an adjustment screw for internal gun pressure for feed to the cap- you can over-adjust and push the same amount as you do thru your gun regulator.......this is not good, and although you may get away with it with two stage paint, with single stage your atomization will suffer- thus orange peal.
I have 7 different guns that I use when I work........for color I use my Iwata, clears I like my Sata......jambs Devilbiss (all HVLP) and for high pressure work my Binks (large flake) even though they are now outlawed here in Wa.
They all adjust differently- but your cap pressure for HVLP is 10, almost always. I have seen people push too much pressure thru HVLP guns & blow the seals out.
If your using HVLP then you need to get a set of cap gauges....your higher quality guns come with them. Some you have to buy them seperate, but you do need them. How can you tell where you are if you don't know where you started??
I guess what I'm trying to say is it's two different settings- done at two different places on your gun.
oohhhhhhh,
ok, well I haven't been using the regulator that screws on the gun, only because my comp. has one and I figured the line pressure couldn't be dropping too much in that short length. I don't know what I have at the cap though. I've just been adjusting it so it looks like it is spraying right, it obviously isn't though. It is HVLP by the way.
I'll have to get a cap pressure guage before the spring when I start painting again.
Either that or I can just name my car the "orange peel Mobile" and pretend like I made it that way on purpose.
Thanks guys.
Where can I get a good cap guage?
Your local auto paint supplier can get one for you, and don't forget to get a Viscosity cup