Finishes, drying and curing

Just about every type of finish you can get will say something along the lines of "dry after 6/ 12 or 24 hours"..
Where as this may be true, the finish wont be cured.

Curing is the process of gassing off of all the solvents as well as the cross linking polymerisation.
This takes time, typically 20 - 30 days.

So, regardless of what finish, be it Nitro, rattle can Acrylic, Poly or even Dingotone you are best served to leave it for a minimum of 20 days before final cut, polish and assembly.
To do so before this curing time is to court disaster.

If you want a finish that you can spray cut and polish and assemble in one day, you will need to look at UV cured finishes. Expensive set up costs, highly toxic and not easy to get right without a lot of practice.

Remember, building a Guitar should be an exercise in patience..
The more time put in during the sanding and finishing process, the better the result.

Typically it takes me around three months to complete a build, whether it be a kit or one of my custom builds.
Most of this time is spent watching paint dry.... but the end results are well worth the time.

Sagacious words of wisdom. As a mod and judge, I've seen a few rushed jobs on the forum - best thing is to step back and take time - give it a chance and the finish will be heaps better.

This is something I should pay close attention to, since I'm equally as guilty of rushing things and not excercising patience, and I'm humble enough to freely admit that.

Greetings Dingobass and any of you other veteran builders!

I'm going to start an EX-5 basswood body bass guitar build in a few months when the weather here improves. I am prepared for a 3-4 month build, no problem. I'm a little confused on the process. Is this right or wrong:

1. Sand the body with sandpaper working up to the higher grits.
2. Rub in a grain filler, sand smooth. Do this several times.
3. Use sanding sealer, sand smooth.
4. Spray color nitro coat, wait until it cures, sand. (How long between coats does one wait to sand?)
5. Spray again, sand, repeat, spray, sand again, how long does one wait? 20 days between coats???...or is the 20 days just for the FINAL polishing?
6. Spray clear coats, sand, spray, sand, repeat, final polishing.

Does anybody use primer? Grain filler and sanding sealer seem to make primer unnecessary.

I can't find any straightforward instructions on how to do a solid black nitro paint job.

Oh yeah....drill the holes for the bridge BEFORE wet sanding (and risk wood swelling....I saw on a Pit Bull video that a workaround is a drop of lacquer in the hole) or after guitar is finished (and risk damaging the finish on the drill press)?

Sorry if these are stupid questions. I am a bit of a noob.

You missed the most important, and vital first step....
Do a mock build, and check that the scale length, and alignment is correct, and ensure everything that's supposed to be in the kit is there.
There's no point doing everything else if your neck pocket is out is out of alignment, or the neck doesn't fit etc.
Check out the recommended build process here >> http://www.buildyourownguitar.com.au...splay.php?f=57

Quote:

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Originally Posted by Zandit75

You missed the most important, and vital first step....
Do a mock build, and check that the scale length, and alignment is correct, and ensure everything that's supposed to be in the kit is there.
There's no point doing everything else if your neck pocket is out is out of alignment, or the neck doesn't fit etc.
Check out the recommended build process here >> http://www.buildyourownguitar.com.au...splay.php?f=57

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Oh, I failed to mention I did an unboxing video, inventory, and mock build already. We're good to go. I'm super impressed with how tight the neck fit is. It's light years ahead of the old bass I'm playing now. Yeah...the EX-5 is a keeper.

Brother, MY most important step is making my lovely bride happy this weekend by getting my garage in shape for this project!!....I'm ashamed to say it's looking pretty bad but I digress....I can't start spraying anything until it gets warmer anyway.

Haha, yes that bit of information would have been helpful, so I don't look like a know-it-all!!
Good to see you have the "Happy Wife, Happy Life" mantra down pat!!
I can't help much with the other info, I haven't down a solid colour build yet, and I certainly have not used nitro.
Hopefully someone will chime in soon for you!

Quote:

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Originally Posted by Zandit75

Haha, yes that bit of information would have been helpful, so I don't look like a know-it-all!!
Good to see you have the "Happy Wife, Happy Life" mantra down pat!!
I can't help much with the other info, I haven't down a solid colour build yet, and I certainly have not used nitro.
Hopefully someone will chime in soon for you!

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Absolutely! 😀 I'm reading all kinds of stuff about nitro. Not much is there about the drying time needed between coats. I want to go with nitro because it's "traditional", used by Gibson, and looks very high quality when done right. The kit is worthy of the best finish possible. I'm also agonizing over buying a better bridge before I start drilling holes. The one it comes with seems just OK...I'm on the fence about it. The kit also seems worthy of a Graph-tech nut but I can do that after completion.

I might get that book by Dan Erlewine from the library about guitars. I read it years ago and recall his in depth discussions about the process.

I'll keep you posted, thanks for the reply!!!!

There's a lot of different info out there about suggested time between nitro coats. Minimum time seems to be about 20 minutes, maximum time 60 minutes. Normally 3 coats a day maximum, then let it dry and harden overnight. Very important to let the finish harden before you attempt to polish it. 1 week is the bare minimum, but 2 is more normal and 3 would ensure that it's ready. High humidity slows drying times, so if that's the case, go with the longer drying times. Too hot a day (say 35°C+) can be a problem as the spray can dry in the air and go on rather powdery. Too cold (generally below 14°C), or too humid when spraying, and moisture can/will get trapped under the finish and turn it misty. So it's best to spray with the temperature in the twenties and with reasonable levels of humidity (if possible).

Note that Nitro is hazardous to health, and you need to buy a vapour mask and should cover up as much as possible to stop it getting onto your skin - wear rubber gloves or disposable latex or vinyl ones. If you can smell the spray with the mask on, then it's either not seated well enough on your face, or the carbon filter is all used up and it needs replacing. The vapour is also explosive, so use a well ventilated area and no smoking or sparks. The finish touch dries in about 5 minutes, so if you are spraying in a garage (to avoid as much dust as possible), then I'd spray, shut the outside door for 5 minutes, then open the door again for ventilation to disperse the fumes. Any door to inside the house should remain closed as you don't want the fumes inside.

The StewMac/Dan Erlewine Guitar Finishing book is a very good reference book, but it does spend a lot of time on talking about how to match various classic (mainly Gibson and Fender) guitar finishes. A lot of the information is already available on the StewMac website - you just have to look round for it.

Thanks for the very informative post, Simon and thanks for taking the time to write it. I'm going to build a spray booth out of some scrap lumber and am going to spray in the garage. I agree with everything you said and own a great painting ventilator mask.

Still one question. The time between coats. Does that include sanding between coats?

Or does one spray a coat, simply wait an hour or two, spray another, repeat, then wait 2 weeks or more for sanding, polishing, etc?

Yeah....I need to buy the book.