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Nitro finish curing problems

Posted: Wed Aug 16, 2017 10:46 am
by Robert Freemond
Just finished my first serious Lacquer job & it's not curing. After three weeks I sanded & buffed it out to a very nice finish, but after a couple of weeks you can see that it's still moving.
I now know that I put on too much too soon so - will it ever cure Or should I just strip & start over.

Re: Nitro finish curing problems

Posted: Wed Aug 16, 2017 11:09 am
by Barry Daniels
What brand?

Re: Nitro finish curing problems

Posted: Thu Aug 17, 2017 12:10 am
by Robert Freemond
Lawrence McFadden

Re: Nitro finish curing problems

Posted: Thu Aug 17, 2017 8:13 am
by Aaron Helt
What do you mean by "moving"?

Re: Nitro finish curing problems

Posted: Thu Aug 17, 2017 11:09 am
by Barry Daniels
When you say McFadden's it means that the lacquer is several years old. Usually that is not a problem, but it is something to consider.

So, how many coats did you apply, how thick is the finish, and how much drying time did you allow between coats? What did you use for thinner? How humid is it in your shop?

Re: Nitro finish curing problems

Posted: Fri Aug 18, 2017 11:46 am
by Robert Freemond
Hi every one & thanks for the response.
Berry,
The Lacquer was a couple of years old, I used Home Depot Thinner, I'm in So. California, It'b been Hot & the humidity varies daily.
My paint schedule was: First 2 coats thinned 50/50, following coats every 1-1/2 hrs. for a day.
second day - sand & repeat. for 3 days.
I have since learned that It was too much too fast so my question is, will it ever cure, or should I start over

Aaron, A couple of weeks After I sanded & buffed, the surface was becoming textured & was no longer perfectly flat.
Today if I press hard with my thumb nail It will leave a small mark.

Re: Nitro finish curing problems

Posted: Fri Aug 18, 2017 12:25 pm
by Barry Daniels
The cheap big-box thinner is likely the problem. I had an issue with it once and it messed the lacquer up good. I had to refinish. It's a good idea to use quality thinner and I followed someones recommendation to go with Sherwin Williams thinner. SW has thinner with various degrees of retarder that is useful in my humid conditions in Houston. They provide thinner for professional finishers who are more demanding than the diy folks.

I would say that if your finish is still soft after 3 weeks, it will never cure properly. You will probably get a cured finish quicker if you strip and refinish.

Re: Nitro finish curing problems

Posted: Fri Aug 18, 2017 12:58 pm
by Aaron Helt
Yep, agreed. Home store lacquer thinner can have anything in it. I bought a consumer brand name from a store one time that was oily and had a orange tint to it. I used it to clean stuff but no way I'd put it in lacquer. Crown and major paint manufacturers have the real stuff.
As far as if it will harden up in time, only time will tell.

Re: Nitro finish curing problems

Posted: Fri Aug 18, 2017 2:36 pm
by Robert Freemond
Berry, what's the purpose of using a retarder in humid weather.

Re: Nitro finish curing problems

Posted: Fri Aug 18, 2017 3:17 pm
by Barry Daniels
Retarder slows the curing so water has a chance to get out of the finish. This prevents blushing. Many lacquer thinners have retarders in them. The Sherwin Williams thinner I use is formulated for humid climates by including a certain amount of retarder.

You may not have had blushing in your lacquer, but eventually you will when the conditions are right.

Re: Nitro finish curing problems

Posted: Tue Aug 22, 2017 12:23 pm
by Robert Freemond
If Lacquer can so problematic what do you folks think of Water based lacquer like KTM 9 ( I know it's discontinued).

Re: Nitro finish curing problems

Posted: Tue Aug 22, 2017 1:18 pm
by Aaron Helt
IMO, nitro lacquer is the easiest, most trouble-free finish there is.

Re: Nitro finish curing problems

Posted: Tue Aug 22, 2017 3:32 pm
by Gordon Bellerose
Robert Freemond wrote:If Lacquer can so problematic what do you folks think of Water based lacquer like KTM 9 ( I know it's discontinued).
I use water base lacquer only.
I find it easy to use, easier than nitro to deal with, (fumes, extreme flammability, clean-up) and readily available.
I have not used KTM 9. I have used Target EM-6000, and am now using Britetone.

Here in Canada, our VOC laws are quite strict. There are many conditions that must be met before you can use solvent based products.

Re: Nitro finish curing problems

Posted: Tue Aug 22, 2017 5:50 pm
by Barry Daniels
Making a blemish free, high gloss, quality finish is a challenging process no matter what kind of finish you use.