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Nitro Cure Time


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Hey, I've been waiting for my guitar to cure for some time now (22 days so far with a fan pointed at it rotating the guitar every day so the fan gets the back and the front equal amounts) and it's driving me totally insane!

Stewmac's lacquer tutorial says that a week before sanding and buffing is fine time to wait, meanwhile I was talking to a number of other builders and they say that's a BAD idea (so I didn't) but after talking to them and after searching the forum for "nitrcoru e" and variations of that a number of time and reading all that comes up there's really been no definative answer. The question is: How long do you wait after spraying the last coat of nitro (Deft in my case) before you do the finish sanding and buffing? How much after this buffing do you wait before actually installing all the goods and getting to playing it??

The definative nitro cure time answers is _______ ?

Chris

PS: Named very nicely for everyone's ease in future searches :D

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When you need answers you have to go to the source. Click on the product specification sheet for their clear laquer wood finish.

http://www.deftfinishes.com/wood/clear.htm

They say drying time to the touch within 30 minutes. Of course, it will vary with temp/humidity conditions. Did you use their rattlecan stuff or brushable? I could see a longer drying time if its thinned too much or applied too often/too thickly. If none of those are the reasons then I guess you got a bad batch or you didn't shake the can long enough. :D

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22 days is OK. 5 days is barely acceptable. A month is best.

The longer you leave it, the more it'll shrink, and consequently, the less it will contine to shrink after you've buffed it. As such, the best idea is to have another preoject to keep you busy whilst it cures - that way you won't be chomping at the bit the whole time...

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Did a job with deft and my spray gun. thought I'd save some money but it didn't work out. The guitar was finished in Dec. and still hasn't cured yet. Deft in the can is very thick(made for brushing) and I sprayed it like other laquers. It built up too thick and never cured. Luckily the buyer is a good friend and understood that in a few months he'll get a new paint job on that guitar. Spend the money to get quality stuff like McFaddens. That is all I use now and it dries in 2 weeks easily with no hassle. I bought a lacquer that they sell at wal-mart(deft). I don't think I would have ever bought one of their guitars! Live and Learn..

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If you're going to be spraying something though, make sure it's high quality, which is really the whole point.

You got it!

The reason why they don't want it sprayed is because they already added retarders to it, in order for the laquer not to dry too quick, and it is rather thick. To spray you have to thin it down, once you do this, if you don't know how much, the paint can take months to dry.

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Ahhh, if the answer were that easy, to fill in a blank, but it is not.

The final cure time is dependant on your -entire- finishing system, i.e.:

How many total coats did you shoot?

How much retarder (if any) did you use?

What climatic conditions are you dealing with/living in?

How soon did you apply your new coats over the old coats?

Every factor in the equation has a bearing on your final cure time.

But, if I had to give an answer, and you are looking for PROFESSIONAL results, it would be 2 months, or until you can no longer smell ANY fumes coming off the instrument, then add 2 weeks safety net on top of that, unless you're artificially drying it with heat lamps, or you live in Arizona or Texas maybe.

PS, using a fan will slow it down, fanning the body will make it cooler, and lac cure responds to heat, the more the better, up to a point. :D

Start another guitar in the meantime to give you something to do.

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Blowing a fan at the guitar just after spraying it will help evaporate solvents, but doing that for 3 hours isnt going to do much. I'll set the guitar to be fanned down 5 minutes after spraying it, for 15 minutes. I then take the body and place it in my heat box at 150 degrees (f) and let it back for 25 minutes.

Of course, i'm using a heat box. You should be spraying in a room where all overspray gets evacuated out of the room for better drying conditions.

No offense, but it really sounds like you have a lot of learning and reading to do about spray booths, finishes and techniques. Like Drak said, lacquers react better to heat (cure wise anyways). Spraying a fan on it for a few hours can get produce a hard outershell over a soft undershell because the lacquer is dried on the surface, not all the way through. The heat helps all the solvents evaporate through-out the coats. Get reading :D

This is a real good site for info about spray booths and curing...

http://www.asashop.org/autoinc/march2003/collision.cfm

Edited by AlGeeEater
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  • 4 weeks later...

So I went back and watched my Bennedetto DVDs and he lets the nitro cure for the rediculously short time of 2 weeks?! ALSO, his sanding procedure is kinda iffy as well. He uses and ELECTRIC palm sander (i woulda though that'd create sand-through central) with 500, and for areas that won't reach he does it by hand with 600. And that's IT. One sanding pass for all surfaces and he's done?! None of that 400, then 600, then 800, then 1000, etc. business. He does eitehr 500 electric sand or 600 hand sand for certain areas and then goes straight to his buffing wheels!?

Any Comments?

Chris

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IIRC - you can go from 600-800 grit to the buffing wheel, but you have to start with the coarse compound and work your way up. You can start with the medium compound if you finish with 1200-1500 grit paper.

That electric sander story shivers me timbers - sounds like you'd need a ton of trial/error practice to perfect it. I think Drak uses his RO sander with Abralon pads... but then again, he's the Dark Lord of Finish. muuuaaahhhahahahaha :D

Re: heat box curing...

It does seem to work quite nicely, but I forgot to engage the gray matter and didn't --TEST ON SCRAP FIRST-- !!! I paid the price with a few bubbles the first time. I lulled myself into complacency by monitoring the heat box temp/humidity with a remote sensor. It never read more than 128º F, but I think the infrared lamp will heat the surface faster than the surrounding air.

Mike

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The definative nitro cure time answers is _______ ?

I finished a korina jem with Deft lacquer. I applied 3 full cans. I wet sanded after 1 week and buffed with no problems. The nitro continued to cure after I wet sanded and so it settlled into the grain.

Had I waited a month, I'm sure that the nitro would have stayed smoother but I actually like the nitro to settle in the grain like that.

If you want an absolutely smooth finish, use grain filler.

Next time, I'll wait 30 days instead of just 5; that way, it will be easier to buff because it should be harder.

F.M.

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