Lacquer Curing/Drying Before Final Polishing

[klooker]

I think it was John who said he waits 3 weeks (or maybe longer) before final polishing of a lacquer finish.

What are the issues with polishing sooner - like in a week.

The body on my guitar has been drying for a week. I wanted to experiment with the Micro Mesh kit that I bought & I got a little carried away & did the back all the way to 12,000. It looks great but now I'm worried if I created a future problem.

Any thoughts?

Kevin Looker

[naccoachbob]

Kevin, I think the problem is that the finish doesn't "cure" enough in a week.
I'm about to apply a clear coat to an electric I'm working on, and someone told me to wait 5-6 weeks!! before I go to shine it up. His rule of thumb (this is on electrics) is to wait until you cannot smell the finish. Then, try to press a thumbnail into the finish. If it goes in any at all, it still needs to wait.
On my last acoustic, I waited about a week, and the finish was decent, but on the current acoustic, I'm going to wait at least 2 weeks to really make sure the finish has cured.
Like I said, this is my 2nd build, so others with more experience should help here also.
Bob

[tippie53]

this is one of those things you just cannot rush. Allow 21 days to cure . Too soon and you just will not get a good result. Patience is key with this stuff.

[johnnparchem]

21 Days! :( I promised this guitar to my daugther this weekend. Oh well, I will wait a bit

[Mike Franks]

There are multiple issues with polishing lacquer too soon. First of all, the lacquer has not sufficiently hardened after one week, particularly if there are multiple coats applied. The soft lacquer gets even softer under the heat generated by the buffing process. You will have a very difficult time getting a good, level shine and will stand the chance of melting away lacquer in spots.

The other problem is that the lacquer will continue to lose solvent over the next several weeks after premature buffing and your finish will shrink into the grain (even if you have filled it) and also into any inlay, herringbone etc.

I have learned after many dozens of finishes that there is nothing that you can rush with lacquer!

Mike Franks
www.mjfranksguitar.com

[kencierp]

Hi Kevin,
More often then not the technical info I get from the nitro coating manufactures state 7-10 days cure before final level polish. (Some less). I will post the PDF document from Mcfadden when Sean Seabing lets me know how that is done. I may have the one’s from Behlens and Sherwin Williams as well. The Martin factory, I believe, still uses heated “non-catalyzed nitro lacquer and I am almost certain they only wait a few days. I have call in to them and will post the results of that conversation. My formal paint training was at the Williams Paint School in Madison Heights Michigan – primarily acrylic lacquer on metal. That finish could be finalized the next day even without heat --- of course, pores were not an issue. DaveH at one time was a finishing instructor (Rockler I think) perhaps he will chime in with his thoughts.

[tippie53]

While you may be able to hop onto a lacquer faster , much will depend on a few things . Macfaddens is out of business now and I think the formula was sold to another company . If you get on it too soon you will start to see sinks in the finish in about 3 to 4 weeks . This can make the final finish look pretty amateurish. I am looking forward to see what Ken digs up ,but I did find for best results , time is your best friend .
If you use acrylic lacquer , you can get on that in a few hours . I have used Auto lacquers on my electrics for years and love it . Fast , and hard with excellent results . After all , unlike an acoustic , you don't need to worry about finish inferences .

[klooker]

Thanks for all the replies.

I used Deft rattle cans.

I have been paying close attention to the smell. For the first couple of days it smelled strong like lacquer then it changed to a more subtle smell that's sort of like mineral spirits.

For what it's worth, you can wet sand with the micro mesh sheets when it's still pretty soft & they won't clog.

I did a pretty crappy job of grain filling so I'll have to wait & see how much it sinks in when it's finally dry.

This is my first build & I'm sure you all can imagine how much I want to string it up & hear how it sounds. To help tie me over, I ordered a bargain "practice" kit from Jim Hall which is supposed to arrive today.

Kevin Looker

[kencierp]

First I'll start by saying I am a fan satin finish on Guitars --ie-- Lowden --- Kinkade. For sure the advice that the surface will be harder after three weeks is good. But I think your question was your concern of doing something wrong by polishing after a week or so --- if you are done with leveling portion of the job and plan to do no more, it will do no harm. The idea about waiting is so the coatings are done shrinking and then you can sand back to the sink spots. You then start the polish routine when the entire instrument is the same dull sheen -- no shiny dots. Also, if you, as you have said --- done a crappy job of pore filling, no amount of time or polishing is going to correct that condition. At this point you'd need to sand back till the shiny dots show up, then spray on 3,4,5 coats of sanding sealer --- let that dry about a week, sand again, the surface should be uniformly dull -- no shiny dots. Then shoot a few more layers of top coat --- then the waiting begins again.

Or ----- my choice --- use 0000 steel wool and wool wax "Murphy's Oil Soap" and work the surface to an elegant sem-gloss finish -- $.02

[Tony_in_NYC]

Wait. The longer the better. You don't want your soundboard looking like a washboard!