What would cause wrinkles in curing lacquer, besides oil and surface contamination? I was using my new precat nitro (with a booster catalyst) today and noticed that on a few of my back panels, I got some pretty wicked wrinkles. The lacquer went on smooth, then the wrinkles appeared when curing. I had just finished spraying an entire cab with no problems at all.
The only things I can think of that I did different on these pieces was shoot the lacquer pretty heavy, and I didn't lay down a misted tack coat first. Can this make that much of a difference?
Might this also have something to do with the fact that I'm using a boosted precat lacquer? The lacquer seems to dry really quickly, and I'm getting a lot of overspray. I'm using this lacquer unthinned, too. What should I do - thin the lacquer, or retard it? I'm not getting orange peel, and it seems to be going on just fine. I just don't want any more wrinkles.
From contributor J:
I'm not familiar with this lacquer, but it sounds to me that you are dealing with a critical recoat time. That, or… If I remember correctly, didn't you add more catalyst to the second coat or were you just recatalyzing part of the batch from yesterday?
Rule #1 in finishing: Don't celebrate until the job is done and the check is in hand. (It's bad luck!) You've got a solvent reaction creating the wrinkling. Talk with your rep or a finisher familiar with this pre-cat, who will give you advice on what you should do.
If you put down a heavier coat than usual and then sprayed the next coat before it had a chance to cure enough, that would cause the problem.
Get the technical data sheet for the lacquer you're using and find out the recommended wet mils per coat and re-coat time. If the temperature is lower than listed on the tech sheet, the humidity is higher, or you use retarder, allow more time between coats than the sheet recommends. Check how heavy you're spraying the finish with a wet mil gauge and stay under the limit.
Contributor J, the brand of pre-cat I use can be catalyzed the same way. That basically makes it a post-cat. It cures faster with the added catalyst.
So if I did exceed the wet mils limit, this could have caused the wrinkles?
Do you think that product curing too fast could have anything to do with this problem? Fast cure is the goal, but I don't want to cause any more problems.
Like I said, other than this weird little problem, this stuff is perfect. I'm just trying to figure out what caused it so I don't have to go down that road again.
Keep the first coat within the manufacturer's limits and give it enough time to cure before you spray the second coat. For example, if the manufacturer says to apply a 4 mil coat and allow it to cure for 3 hours before recoating, but you sprayed a 6 mil coat, you'll need to wait longer than the 3 hours.
Contributor D brings up a good point that may be involved. Is there a waiting period before you can use the lacquer after catalyzing (induction period)? Did you measure the catalyst precisely? Stir it in very well?
Like I said, the only things I can think of that I did different with the pieces that wrinkled were that I did not tack coat, and I basically just shot a heavy coat on the piece. With my other cabinet, it turned out fine. With that, I just kind of built up the layer slowly - misting on layers till I got the thickness I wanted.
I'm thinking that I should just build up the layers slowly from now on. I'm also considering retarding the mix just a wee bit to get a little better flow out and less overspray.
Give Trinity tech support a call and find out if there's an induction time with the booster catalyst, if the LC-209 is self-sealing, what the max recommended wet mil thickness is per coat, and max number of coats (max dry film thickness).
The viscosity is pretty low, so it shouldn't need to be thinned depending on your spray equipment.
Tech support should be able to tell you how to avoid the wrinkling. Spraying a number of light coats instead of a couple wet coats isn't a route I'd want to take; too time consuming.
My paint supplier told me I wouldn't want to exceed 3 coats of this product, as the surface might be prone to crack otherwise (due to high solids). I'm using 2 coats of Trinity's vinyl sealer under this, and he took that into account.
For what it's worth, it was coat number two that did the wrinkling. The first coat had dried overnight.
I don't know… I'm still wondering if this lacquer's super high dry rate has something to do with it. That's why I was considering using a bit of retarder. It would help with the overspray, anyway.
If you have to turn the air pressure up too much to atomize the finish, causing excessive overspray, then a little lacquer thinner will make it atomize at a lower pressure and reduce the overspray.
I'm going to try again tomorrow shooting lighter coats, and after letting the pieces sit in our hot room for a couple of days.
Besides getting a little harder finish with the booster catalyst (this may be also the reason that it dries real fast, besides being formulated with acetone to reduce V.O.C. emissions), why do you feel the need to use this? After all, it is a pre-cat, correct? I'm thinking this booster catalyst is a little too hot and temperamental in its effect within this system. Just cut out this stuff and it saves you a little money. No worries about wrinkling and everything is back to normal with a pre-cat that dries quicker than your previous brand.
Keeping it wet too long on fresh coats at the narrow end of the window is also a problem. Retarder will increase the problem, as it lets the second coat have more time to react or soften the first coat.
If you didn't over-catalyze one coat and boost the other coat, they both have different windows and the hot acid in the catalyst just eats the uncured other coat, again allowing crinkle.
I've never added catalyst to a pre-cat. You can end up with it blossoming, much like a wrong mortar mix will effervesce through tiles forever. You have to just redo it or you might get by with a sand and recoat with a proper catalyzed mix.
If you have a 10-1 ratio, it's even more critical to be dead on with the mix, as opposed to a 1-1 ratio. Being off a little in 1 to 1 isn't much, but being off a little in a 10 to 1 ratio can be 20%!
Comment from contributor A:
Chances are you selected the wrong tip size and it became way too heavy causing it to curtain/wrinkle. My golden rules are: You can always put more on but you can't take too much off and always shoot a piece first and wait to see how it is going to react to the environmental aspects (humidity, temperature, etc) as lacquer can be deceiving from day to day depending on your environment.
Also, if you shoot a light tack coat and then come back to it a little later and spray a fill coat it always helps it hang on better. This helps especially if you are shooting clear high solids instead of high build lacquers. Another thought is maybe you used a lacquer sealer like a vinyl lacquer sealer that was not copolymerized with a small amount of amino resins. If you did this there is a chance that the acid catalyst attacked the non catalyzed vinyl sealer. There is so much to know from product to product and it is so easy for things to fail.