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Accerate Nitro Lacquer Curing Time?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=21797		 Page 1 of 1
Author:  cyrguitars [ Sun Apr 05, 2009 6:25 am ]
Post subject:  Accerate Nitro Lacquer Curing Time?
Is there a way to accelerate the curing of nitro lacquer? I normally wait 3 to 4 weeks after application before final sanding and polishing, but with the instrument I'm working on I'd like to get it done faster - under a week if at all possible. I've heard that infrared lamps can speed up the process. Is this true, and if so, how does one do it?

Thanks!

--Steve
Author:  woody b [ Sun Apr 05, 2009 6:36 am ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Infrared lamps are often used in automotive body shops, but I'm not sure the radiated heat would be good for a guitar.
Author:  DannyV [ Sun Apr 05, 2009 11:38 am ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
What about post cat lacquer? I used it on my latest effort just because I had some and buffed out after a week or so. Seems OK but I don't really know that much about it and the body is maple. I'm just trying out some alternatives. If anyone has some thoughts on post cat I'd be happy to hear them.

Cheers,
Danny
Author:  Howard Klepper [ Sun Apr 05, 2009 12:23 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Fast and good do not sit easily together in finishing. Unless you are doing UV cured polyester.
Author:  cyrguitars [ Sun Apr 05, 2009 6:10 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
DannyV wrote:
What about post cat lacquer?


The nitro lacquer is already on. From the comments here. it sounds like I have no alternatives but to wait.

Thanks guys!

--Steve
Author:  SniderMike [ Sun Apr 05, 2009 10:37 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
I feel like if I scuff the final coats with 600, it creates more surface area and cures a bit faster. I have no proof of this, however. It's just something I feel in my loins.
Author:  tubeman426 [ Mon Apr 06, 2009 12:18 am ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Hi, actually when you scuff it with the 600 grit you are opening up the pores in the finish, which allows the solvents to to escape the finish quicker.
I my self use mohawk nitro lacquer, I wait about five days then wet sand with 800 grit, then lightly machine compound, then hand polish. Its way less work when the finish is still a little soft, you just dont want to use any preasure when you compound the weight of the polisher is enough. I find its a quarter of the work over polishing a four week old finish.
This works great for me, but you cant get agressive or you will smear through.
Hope this is helpful,
Terry...
Author:  Fred Tellier [ Mon Apr 06, 2009 11:39 am ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
The Cocobolo 000 I completed last week was the first I was patient enough to wait the full 4 weeks as I was going to buff for the 1st time on a buffing wheel setup and was nervous about damaging the soft lacquer.
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=21746
I flattened the finish after about 18 days with 3m 400 gold disks on a round automotive block and could not believe the lacquer smell I released by this. I gave the guitar another week and went to 800 wet again releasing solvent smells. I gave it several more days and went with 1200 then 1 day to 2400 then 1 day to menzerna fine then 1 day to extra fine. This is by far the best finish I have produced and am glad I stretched it out to the full 4+ weeks.

It was easier to wait this time as I was building 2 guitars at the same time so I worked on the second while I waited. I will start spraying the 2nd today so early or mid May will be buffing time.

Fred
Author:  Howard Klepper [ Mon Apr 06, 2009 11:46 am ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Lacquer doesn't have pores, but scuffing it will give it more surface area. The question then is whether what is taking the time is solvent evaporation from the surface or solvent migration to the surface. My intuition is that it's the latter.
Author:  Michael Dale Payne [ Mon Apr 06, 2009 1:07 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
A couple years ago I UV cured a nito finish for 4 days using 4 uv lights about 20" from the surface on a timer. on for an hour off vor an hour and so forth for the 4 days. on the 5th day I leveled out and buffed. It looked super. I intonted and played it for a week before shipping out. about 5 days after I shpped it It came home. the finish had shrunk back and the case material had left impressions in the finish. Very very faint but ther none the less. After that I never again rubbed out a nitro finish in less than 24 days.

I am with Howard here. The solvent is migrating through and out the surface. you can't really rush it and expect the same result.

Now My wife and granddaughters bought me a Mac Ebony and sinker Redwood Belluci Classical a year and a half ago. After they gave it to me I had a conversation with Belluci about the finish. He told me that it was as I new aready a hand rubbed nitro finish, and he claimes his finish guy takes 2 days to apply and rubbes out on the 7th day. The guitar is now a year and a half old and looks great but it has shrunk back some. I can feel a fain edge at the back seam but all and all it still looks great it is odvious that the finish has shrunk some.
Author:  Mike OMelia [ Mon Apr 06, 2009 3:40 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
I am kind of curious why a UV light would have any impact on Nitro.

However, since Acetone has a lower vapor pressure than water, it seems likely a low pressure chamber might be useful in speeding up solvent release. Keeping the pressure above the partial vapor pressure of water should insure the guitar does not dry out.

One way you could know you were above the vapor pressure of water would be to put a glass of water in the chamber. If it is "boiling", you are too low.

Thoughts on my lunacy?

Mike
Author:  Michael Dale Payne [ Mon Apr 06, 2009 3:51 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Mike O'Melia wrote:
I am kind of curious why a UV light would have any impact on Nitro.

However, since Acetone has a lower vapor pressure than water, it seems likely a low pressure chamber might be useful in speeding up solvent release. Keeping the pressure above the partial vapor pressure of water should insure the guitar does not dry out.

One way you could know you were above the vapor pressure of water would be to put a glass of water in the chamber. If it is "boiling", you are too low.

Thoughts on my lunacy?

Mike


I miss typed oops_sign I ment IR infra red oops_sign UV will not have an affect IR does soely because it rasies the surface temp.
Author:  Mike OMelia [ Mon Apr 06, 2009 4:18 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
IR Lamp... Yes! Of course, all incandescent lamps are "IR Lamps" in that they emit radiative energy as well as visible light. A true IR lamp would look no different on or off unless it got VERY hot... which means you could also point a hot plate at the guitar as well.

Was thinking more about the vacuum chamber idea. It should work. But I think you would want to wait a day or so before using it since you would not want the finish to bubble. This sounds like a great idea for an experiment.
Author:  Michael Dale Payne [ Mon Apr 06, 2009 4:47 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
I am talking a true IR lamps or at least the common (red heating lamp) the mid wattage ones that are used to keep food hotat the junk food places like Arby's. Yes they will get very hot. Hince the on off cycling I did.
Author:  Michael Dale Payne [ Mon Apr 06, 2009 4:50 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Michael Dale Payne wrote:
I am talking a true IR lamps or at least the common (red heating lamp) the mid wattage ones that are used to keep food hotat the junk food places like Arby's. Yes they will get very hot. Hince the on off cycling I did.



not sure what i said that made you think incondesent?????
Author:  Mike OMelia [ Mon Apr 06, 2009 4:57 pm ]
Post subject:  Re: Accerate Nitro Lacquer Curing Time?
Michael, Just kidding around... all hot sources can be sources of radiative (IR) energy. Even a light bulb.

Now, I am surprised nobody jumped on the guitar autoclave I was suggesting. Its amazing how much force will get applied to a container big enough to hold a guitar when a vacuum is applied. Partial pressure of Acetone is ~6.8 psi.

Mike
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