Stewmac nitro schedule

[burns12]

I don't know if anyone else has seen this, but on stewmac's finishing schedule for nitro lacquer...(link removed)

It says that after 4 days of finishing spraying the lacquer, it is able to be wet sanded and buffed. I emailed them asking about this because everything i've ever heard said to wait at least 3 to 4 weeks before wet sanding and buffing. But the reply I got confirmed it, he said that the finish will continue to cure for a very long time but that after 4 days (depending on amount sprayed) it can be wet sanded and buffed.

Does anyone have any idea if this is true? I would be ecstatic if it was but i'm a little weary here.

Thanks

 

[Wally]

I would let it rest for ahwile longer than 3-4 days....the longer the better. THe nitro won't load the paper up after just 3-4 days, but the longer it cures the less shrinkage will occur after sanding.

 

[surfoverb]

he said that the finish will continue to cure for a very long time but that after 4 days (depending on amount sprayed)

this is key right here. Maybe if you spray like 2 coats in 4 days it will be cured but even a super thin nitro finish is like 30 coats. I just don't see not waiting the 30 days.

 

[Old Cane]

I'm pretty sure this schedule has to do with using the finish in the can and shooting it with a gun, not spray cans like most of us use. My understanding is this makes a huge difference in drying time.

 

[musicalmartin]

It really depends how thick the paint is as the bottom layers of nitro dry slower with thick coats on top as the thinners in all the paint tends to soften it all up for a while .Stewmac is correct but leave as long as you possibly can for safety .I used to let model autos dry for a few days and then polish ,but if you use a wet leveller final coat of almost pure thinners you may not even need to buff it at all as it levels and shines up the top coats naturally .I also used to polish blems out with my fingers while the top coat was not fully dry .Nitro is very forgiving as long as the paint mix is right and the pressure correct .Trouble is this is all a bit of a black art in may ways .I always thought that if I had to polish it, I had failed in applying the top coat .The same principle applies to auto ,guitars ,motorcycles and any nitro finish needing a shiny top coat .I learned a lot watching a friend of mine get a perfect finish on his motorcycle parts .When a bug landed on a part he was spraying .he flipped it out with a finger and then adjusted the gun to fine and sprayed in the blem .He then shot thinners quickly onto the area to level it and then carried on spraying another coat refilling the gun but a bit thinner this time .No sign of bug ,finger marks or depression at all when dry .I made model autos for a living so need a perfect deep shine .I use Poly now but polish it to remove some of the shine on older type classic cars.

 

[burns12]

I'm pretty sure this schedule has to do with using the finish in the can and shooting it with a gun, not spray cans like most of us use. My understanding is this makes a huge difference in drying time.

I am using the spray can nitro that Stewmac sells, you think that might account for the dry time?

I may be under a time restraint here and I can let it dry as long as I can but if this will be fine then I might give it a shot.

 

[Old Cane]

No. My understanding is that if you buy a can, mix it and use a gun and compressor you may be able to buff it out in under a week. If using spray cans wait at least a month.

 

[burns12]

Oh ok I see what you mean now. Why would that make such a drastic difference?

Also I emailed Stewmac again and they're very confident in recommending this schedule for finishing with nitro.

 

[Wally]

Patience is a virtue.

 

[Wally]

burns, if you are in a hurry, follow their recommendations. IF at some time in the future you notice shrinkage of the finish into the pores, then you will understand why curing time is important.

 

[burns12]

I'll have to see how much of a hurry I should be in after I finish the clearing, i'll have a few more than 4 days for sure but not a month. So we'll see.

Also, when you all say shrinkage, what exactly do you mean? Is it irreversable or completely ruin the guitar?

 

[surfoverb]

some good info here:
http://www.tdpri.com/forum/finely-finished/164556-nitro-sniff-test.html

 

[Wally]

As the nitro dries, it 'shrinks'...loses volume. If one sands and polishes before a reasonable time of curing, then the nitro will continue to lose appreciable 'size'. IF it does this, then what once was a smooth finish will reveal the porosity of the mahogany in this case. IF you look at vintage guitars, you will see the effects of this long term shrnkage. IT is just not desirable to see this in a relatively new finish.

 

[burns12]

some good info here:
http://www.tdpri.com/forum/finely-finished/164556-nitro-sniff-test.html

I asked this question in this thread and decided I didn't want to thread jack you so I started this one haha. I'll have to check it out again though.

And ok I understand the shrinkage now, I could potentially have 2 weeks to let it cure, depending on how everything else goes, but thats a maximum.

 

[surfoverb]

I asked this question in this thread and decided I didn't want to thread jack you so I started this one haha. I'll have to check it out again though.

And ok I understand the shrinkage now, I could potentially have 2 weeks to let it cure, depending on how everything else goes, but thats a maximum.

why only 2 weeks?

 

[burns12]

Well I am going out on a 2 week roadtrip/tour type thing with my band and really desperately need another guitar to take with me. This being the other guitar.

 

[Shepherd]

The thing is that nitro is going to continue to shrink the entire life of the guitar. Some say it takes years to fully cure. I did one a year and a half ago and it has some shrinking in it. What I dont understand is if the sanding sealer coat is perfectly flat, where is the nitro topcoat going to shrink to, yet it still does.

 

[burns12]

A very good question that I was pondering to myself as well. What would it have to shrink into? Unless everything shrinks including clear, sanding sealer, stain, grain filler, then it could go into the wood I guess, but that's hard to believe.

 

[mudbean]

The thing is that nitro is going to continue to shrink the entire life of the guitar. Some say it takes years to fully cure.

My 2008 Hot Rod '52 smelled of nitro when I got it last year - it has since lost that aroma. There is some settling of the finish - I'll grab a pic tonite.

mud

 

[Old Cane]

If my memory is still functional I remember WV as being pretty muggy. So, if you let it sit for 4 days and pick it up to start sand and it's stuck to your hand......you might want to borrow a guitar to take on the road with you. Then again, I did about 15 years of road work with 1 guitar. I guess things change. And change ain't always for the better.