NEW! Faster Search Option

Loading

Lacquer cure time

Keef's picture

Lacquer cure time (post #111074)

Quick question:


How long does it take for a Behlen Top Coat spray can lacquer finish to completely cure?  Can implies 24 hours.


Long Story:


I just finished the final last of 15 coats of spray can (Behlen Top Coat) nitrocellulose lacquer on the never-ending Christmas box project.  All I need to do is let the finish cure.  How long should I wait for the lacquer to cure to hardness before I pack it up and ship it?   The first 3 coats went on about 3 weeks ago.  Also, if I were to rub it out (which I dare not even THINK of doing one more thing to this box) how long would I need to wait?


Several days after the previous "last" coat, I inadvertently got a little shellac on the surface.  No problem I thought, lacquer is alcohol proof, so I will wipe the shellac off with a little DN alcohol on a soft cloth.  Really really bad move.  It removed the lacquer as well!  What was up with that?  The more I rubbed, the worse it got- it took off a couple of small spots almost down to bare wood.  I would not have expected that.  As it turns out, just a thorough light sanding/ feathering with 320 and one "last" coat fixed it- it blended right in.


KB

Kevin's picture

(post #111074, reply #1 of 5)

24 hours is a good rule of thumb with lacquer for both minimal time to packing and to rubbing out. More certainly won't hurt. Less would dicey.


With lacquers the "cure" is relative. Some say that lacquer never completely cures. Others say that it takes years to fully cure. It doesn't really seem to matter. What matters is when can you do stuff with it or to it.

loucarabasi's picture

(post #111074, reply #2 of 5)

keef, why soo many coats?


-Lou

As the twig bends- So grows the tree!!
Rich14's picture

(post #111074, reply #3 of 5)

Keef,


I think it's "safe" to rub out nitrocellulose 48 hours after the last application, but I wait a week. I don't know of any tests regarding the hardness of the surface and the final appearance of a rubbed-out finish depending on various "curing times." But that would be an interesting thing to see.


As to how long it really takes lacquers to "completely cure," here's some information. If you finish the inside of a cabinet with lacquer and leave the doors closed, you'll get a strong smell of solvent every time you open the cabinet doors for several years. That's why it's a good idea to finish insides of case goods with shellac.


Rich

Kevin's picture

(post #111074, reply #4 of 5)

I just checked my Sherwin Williams finishing systems guide for recommended dry times before rubbing or polishing lacquers. I only found a few. Several list that they can be rubbed but give no recommended dry time before rubbing. Here's the ones that I could find times for:


24% Solids Finishing Lacquer - overnight


Catalyzed Lacquer - overnight


Precat Lacquer - 4 hours


Interestingly they don't mention rubbing or polishing at all for their CAB-Acrylic lacquer. Do you rub yours? If so, how does it seem to react compared to nitro?

Rich14's picture

(post #111074, reply #5 of 5)

Kevin,


I find no difference in the handling of CAB-Acrylic vs Nitrocellulose in any way. The only difference for my purposes, is that CAB-Acrylic is water-white when applied, and stays that way - it does not yellow, itself. It also seems to prevent or reduce the yellowing that maple is capable of developing.


It goes down, dries, levels and rubs out like Nitro.


I generally level-sand my lacquer applications the following day. I shoot 3 light, but fully-wet coats each day. But I wait a week to rub out after the final coat. I'm in no hurry. I don't have to meet any production schedule but my own. And I know the lacquer is as hard as it's ever going to be (for rubbing) by that time.


Rich