more lacquer questions.............

[Greg L.]

Okay...I managed to get the initial coat on my 69 before taking a breather last week so you could say that now I have my feet wet.

Along with my wet feet I now have some more questions for you lacquer guys, especialy those that use it with HVLP guns. You see I seem to have had a heck of a time getting the lacquer on wet enough and I don't know why. I'm thinking that I was spraying it too fast because I didn't want it to run and have the metalics bunch up...no danger of that one!

The spraying was done at about 67F with about 70% humidity with a Devilbiss Plus(GFG-670) HVLP compliant gun set to about 32 psi at the gun and a 1.3 tip. I tried to set the fan as wide as possible which according to the Devilbiss specs is about 12". The lacquer was thinned to specs(1 part paint to 1-1/2 parts thinner) I then tried to set up the gun as per a procedure from the Southern Polyurethanes, Inc web site which basicaly has you turning out the fluid adjustment(after the fan width is set) from the closed position until it looks even in build. In contrast a Devilbiss bulletin(SB-2-001-F) says to turn the air cap so that the pattern is horizontal and then adjust the fluid so that the fluid is the same across the pattern as judged by the eveness of the runs. This second method has me thinking that it would produce a much wetter coat but that's just me and I might be wrong about that.

Anyways here are some of what I hope are basic questions that can be easily answered. Here goes......

The tech sheet says that drying time between coats should be 5-10 min but it was flashing off in LESS than a minute. Should the fresh paint be "wet looking" until it's in the 5-10 minute window? I'm using DTL876 thinner and it's good for 65-85 degrees and the day I sprayed it it was about 67 so that should have helped and made it flash closer to the 10 minute mark but it didn't. So my first question is how can I get the lacquer to stay wet longer? Is this a gun setting issue or am I spraying it wrong?

I thought that maybe I was moving too fast and that might be so but it only took one coat to cover the primer and I was told that it should take 2-3 coats so why would I have been able to cover the primer with only one coat especialy if I was moving too fast?

I think my quick flashing problems might be with the gun set up but at this time that is just a guess so any advice here would be great. I'm trying to do everything here by the book to eliminate any variables but one major problem it seems is finding good specs for spraying an old product(lacquer) with new technology(HVLP gun). The Devilbiss Plus product sheet doesn't list a tip size or air pressure for lacquer and the PPG sheet only says 10 psi at the cap for a pressure with lacquer and I can't measure that so I'm sort of throwing darts in the dark. The guns inlet pressure range is 30-40 psi so Im wondering if maybe I shouldn't drop the pressure to say 25 psi or so...just guessing that since lacquer is so thin that maybe it doesn't need the higher pressures....any thoughts on that one?

My last question is why do you sand between the coats of lacquer...is it to level the surface to prepare for the next coat or is it for adhesion? The way I understand it is lacquer dries(it doesn't cure) and that the top coat "melts" into the underlaying coat so it doesn't need sanding to "stick". This question is more for my curiosity than anything.

Well sorry for the long drawn out post but I wanted to get as much info as I could to try and make it easier to get some ideas. I don't mind playing and experimenting a bit with pressures and fluid setting to get the gun set up properly but at about $500 a gal and having to drive 7 hours round trip to get it I really don't want to waste it.

I'll look forward to your thoughts.

[Wayne P.]

Re: more lacquer questions.............

I've never shot lacquer with the modern hvlp gun, but here is some other info. You don't need to sand between coats unless you get it excessivily rough or too much trash in it. I would thin at least 200% and I prefer 300%. Lays much smoother. Yes it takes more coats, but less sanding when you're finished.

[Donald T.]

Re: more lacquer questions.............

Greg,

I think you are over thinking things a bit. Lacquer is very forgiving. First thing is to start with some test panels. This is very important because painting is more by feel, and you need to get the hang of it. Set up the spray gun with so paint flows even across the fan. spray different spends and even intentionally spray some runs so you can get a feel for how slow is too slow. Once you get comfortable with the spray settings, distance from the panel, and speed; then move over to the car.

I use an older version HVLP Devilbiss gun - Finishline 2. The air cap states a max inlet pressure of 23 PSI, so you may want to check your air cap for the proper inlet pressure. I also use a 1.3 tip so you should be fine there. Thin according to the specs with the proper temp range - I've even shot outside the temp range, although not ideal it does not seem to be that sensitive as long as it is close.

Wait the appropriate flash time between coats. It may appear to flash off quickly, but keep in mind there is some thickness to the paint. Since it is solvent based and not catalyzed, the paint will dry quicker at the surface. If you don't wait the appropriate flash time, you could risk solvent trapping. Don't get hung up on how wet the paint appears to be on the surface, just wait the appropriate flash time from the spec sheet. I never have sanded between coats as it is not necessary unless you have let the paint dry too long between coats. Just see the tech sheet for max time between coats.

Bottom line - practice practice practice with test panels! Don't experiment on the car. Get confident with your results on a test panel, and then paint the car.

Good luck!

Don

[Alan S.]

Re: more lacquer questions.............

Hi Greg,
I was curious to read what you meant by wet feet. I was afraid you were going to say that so much paint was dripping off the car that your feet were getting wet.
I can only comment on one of your points... the fellow who painted my car had me sand between coats only to perfect the layers of paint as they built up. I think I smoothed the surface some and took a few pieces of fuzz out of the paint. I never got the feeling from him that I was promoting adhesion of the next coat.
Please remind yourself of what Donald said "lacquer is VERY forgiving".
Regards,
Alan

Here's a picture showing the texture and sheen before sanding and after, perhaps this will give you something to compare your work to.

[Bill M.]

Re: more lacquer questions.............

I've never shot lacquer with the modern hvlp gun, but here is some other info. You don't need to sand between coats unless you get it excessivily rough or too much trash in it. I would thin at least 200% and I prefer 300%. Lays much smoother. Yes it takes more coats, but less sanding when you're finished.

I agree. I used 200% to solve the too dry problem, and would go 300% if I had to. I also used the highest temp. thinner. (I was using a siphon-feed gun.)

[Dick W.]

Re: more lacquer questions.............

I would avoid over thinning the paint, especially until the top coat. You will take more material to cover and possibly end up with runs. Adjustment of your paint gun is the secret.

[Jim D.]

Re: more lacquer questions.............

I have always started with slowest thinner and used retarder if it still didn't flow out well. That method results in very little sanding and polishing.

Jim

[Greg L.]

Re: more lacquer questions.............

I think we need one of those little "Smiley" thinks showing a guy pulling his hair out!

I didn't think that the sanding between lacquer coats was for adheasion so now I know for sure that it isn't. The body will have to be sanded to clean up the dry spots and level it in general but now I know that I don't have to get too carried away in the nooks and crannies of the door jambs, etc ,etc.

I had thought that over thinning would help the "wetness" problem but I also thought that it would be best for a first timer to stick to the PPG and Devilbiss recomendations so that I don't go and create my own set of problems.

I could try and thin it out a bit more but is there any other way to get it to stay wet longer other than by overthinning it that much(I would like to stay close to the PPG recommendations if possible)? The temp range for this thinner is 65f to 85f so what if I were to wait until it gets cooler out and spray it at say 55f? I guess I could also spray closer or slower but I was afraid of putting it on too wet and before I knew it the car was painted...

Speaking of painting speed, how fast is too fast? I read someplace that about 1 foot per second is about right but I'm sure that they weren't refering to lacquer. My buddy back home showed me how fast he paints cars but he has never sprayed a fast drying paint like lacquer so he may have the same "dry" problems that I had if he were to try it. Granted, he could probably quickly adjust his technique to get it to stay wet like it should.

As far as it laying flat I think it's fine. I can't see any orange peel what so ever. Even the dry spots look level but they are not smooth to the touch. They feel like they have dry overspray on them. The only smooth spots are on the trim pieces and rear filler panel that you see hanging in the one pic and low on one fender where I held the gun at the spot for too long....no runs or mottling but the spot is smooth, level and sort of semi gloss so I'm thinking that is what the whole car should look like if it was sprayed properly.

I know that lacquer in a solid color is very forgiving but this is silver so maybe I should practice a bit. I also need to know that my gun is set up properly so I guess I'll have to play with that some more too. I was thinking that I could practice on my Corvette because it was supposed to take 2-3 initial coats to cover but it was covered in just one so there goes my practicing!

Right now it's ready for final sanding and the final "coats" and with my last results there is no way I am going attempt that at his time.

If you all could help a bit more with my last set of questions that would really help. I don't know what you can tell from the pics but I thought it wouldn't hurt to attach them anyways. Does the dullness look about right? The dry spot on the door was about as bad as it was and as you can see it was very bad. I don't know why it was just to the rear and above the body line...maybe I pulled the gun away too soon???

I sure hope my next crack at this is much. much better.

If not I guess I'll be ordering a bunch more thinner and maybe some paint and then get ready for another 7 hr paint run to Montana.....

[Jim T.]

Re: more lacquer questions.............

Greg I painted my 70. Used Dupont lacquer, Donneybrooke Green. I used a suction gun so what follows are only what I did. Painted two coats on the carport in Nov 1990, day to paint was the one I had been waiting for. By the time I got the sealer on, I had only time enough that day to spray two color coats. Waiting for another perfert day for me to spray again did not come untl Mar 1991. I did not sand between any of the coats. Just tack clothed it again in March for the final two coats. Later used 1200 and 1500 to wet sand and followed with Dupont polishing compound. If it was my door's paint condition on the first coat, I would sand the spot on the door before putting another full coat on.

[Alan S.]

Re: more lacquer questions.............

Hi Greg,
I'm sorry I can't be more help. You're pictures really SHOW what you've been describing and asking about. I'll bet you get some GOOD advice now!!!
Regards,
Alan

PS: I like the lights in your paint booth . Is that something you rigged up for this project?

[Greg L.]

Re: more lacquer questions.............

Thanks Alan, ya that was a quickie set up for the intital coat. I have a 12' board nailed to a saw horse to support a like set of lights on the pass side. I plan to buy about as many lights as I now have but in the three light fixture style to replace the two lights ones that you see. Just thought it would be better for the final coats.....which might be next spring at the rate I'm going.

I might be down about how my first attempt worked out but I'm not out yet!

[Mike M.]

Re: more lacquer questions.............

Greg,
The finish on the first pic looks like too much pressure, holding the gun too far from the surface (drying before it hit hits), slow motion and most importantly, too fast of a thinner (also thickening and drying before it hits). Use the slowest thinner you can find for better flow.
You mentioned ambient temps, of equal importance is the humidity.
Increases in humidity will also aid the material flow and gloss.
HaND

[Alan S.]

Re: more lacquer questions.............

Hi Greg,
Don't be down at all!!! Remember I'm the one who thought your feet were wet with paint. (Joke, Joke)
My restoration ran on for many years. Often I'd come up from the garage in my basement and my wife would ask "did you make any progress ?" and I'd say "no, not really". She'd say "does it matter?" and I'd say "no, not really".
I thought it would be done for it's 25th birthday, it turned out to be it's 35th. But WHAT FUN I HAD. IT SOUNDS LIKE YOU'RE HAVING FUN, TOO!!!
Regards,
Alan

[Greg L.]

Re: more lacquer questions.............

Ya thanks Alan it's just that some days I think I'm in over my head with painting. Body and prep I have no problem but painting is new territory for me.

I had to laugh when you said that it sounds like I'm having fun because the first thing that poped into my mind was a line from American Graffiti. It's towards the end and Toad and Debbie are both sitting on the sidewalk in front of Mel's. Toad looks like hell from all that's happened and Debbie says to him that he should have told her about his Vespa earlier and then they "wouldn't have had to go through all the FUN".

[Greg L.]

Re: more lacquer questions.............

Thanks Mike. You say it looks like too much pressure and you know I'd swear that it seemed to spray wetter with the inlet pressure around 25 or less psi but that was out of the design range for the gun so I cranked it back up to 32. The guns range is 30-40 but maybe since lacquer is so thin compared to modern paints, this 30-40 doesn't apply to lacquer.

Does it make sense that thinner paints like lacquers require less air pressure to properly atomize than would modern urethanes or BC/CC ?

Is it acceptable to use Dupont thinners with PPG paints? I know it's not recommended but does it work? You can still get lacquer primers and thinners up here but only in Dupont so if I can mix the two I'm all for getting a slower thinner.

If I can't get a slower thinner will spraying it at a cooler temp like say 55f with a thinner that is meant for 65f-85f help?