Issues with rattle can lacquer curing

[pfox14]

I used to spray my lacquer with a DeVilbis gun, but it broke and I switched to aerosol lacquer. The main problem I had with using a conventional spray gun was I wasn't getting enough build-up with light coats and would scuff right through it. I tried various mixture ratios of lacquer and thinner and even tried some slow curing thinner. The results were unsatisfactory.

Anyway, I love the build-up I get with the rattle cans. I can spray 4 light coats and it will level nicely, and I can easily scuff in between without sanding through. I usually wind up spraying 10-12 coats in total, but this stuff won't cure even after 2-3 weeks. I just shipped out a guitar that I let sit for 3 weeks before final buffing and polishing, and the customer sent it back, because the lining in the case left impressions in the finish all over the back, especially the back of the neck where it rested against the neck support inside the case.

Anyone have a solution? Increasing cure time to 5-6 weeks seems unreasonable.

[Jeff Hildreth]

What brand was the rattle can lacquer? Re Ranch ?

[multidon]

As you have already noted, your coats are thicker than they used to be. I suspect that your coats are skinning over which prevents proper cure through. This is only a guess on my part but instead of spraying 4 coats in one day maybe you could try just one coat a day with drying at least overnight or maybe even 24 hr. Taking 12 days to spray seems preferable to waiting 6 weeks to cure.

[thistle3585]

I'm curious to know what brand you are using. I have sprayed Deft for years using an HVLP and have used the rattle can version from time to time and noticed the same thing happening with my last couple builds. I wondered if it was a change in their formulation. I'm guessing that its drying but reacting with the case material. I laid an instrument in the case and it imprinted but had another from the same batch laying on a cotton towel with no problems. I am now experimenting with new lacquers.

[Michael Lewis]

Spray a good coat and let it skin over so you can scuff sand it and let it gas off at least over night if not a couple days before applying the next coat. If you build too much finish it will take forever to get hard. Also it may be the age or formulation of the lacquer. Old lacquer can remain soft enough to imprint for years. Rattle cans should have a date code somewhere, or call the manufacturer.

[pfox14]

I am using Rustoleum clear lacquer. I think you guys are right...4 coats in one day is too much, even with 1 hr. in between each coat. I never use old lacquer cans. I start with fresh stuff for every instrument, so I don't think it's the age. Another thing that amazed me is when I got the guitar back after 8-9 weeks, it reeked of lacquer when I opened the case. Obviously it was still off-gassing even after 2 months.

[Michael Lewis]

Check the label to find what sort of lacquer it is. I would guess at this point it is acrylic and not nitrocellulose. It may never get hard.

[multidon]

Rustoleum spray lacquer is the same product as Watco. They market the same product under two different names. It is nitro with alkyd resin, which actually makes it a lacquer varnish hybrid. There is also an acrylic spray lacquer by Rustoleum that is found mostly in auto parts stores. So I think this is the nitro product. By all accounts this should cure rock hard. I don't think the product is the problem, it's the process.

I wonder if that alkyd resin makes it less repairable than all nitro. Would the alkyd component affect melt in?

[Michael Lewis]

Auto finish. Untraveled territory for me.