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I purchased a couple of infared medium wave curing lamps, like those used in automotive painting. It definitely seems to speed up curing.

I was wondering if anyone is using a similar sytem and what you have learned so far????

I tried on once and cooked/bubbled mt finish, KTM9 so I haven't tried it again.

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Tickle your guitar daily, and it'll tickle you back.

I have had two guitars in there for several hours. Been checking to make sure that doesn't happen. I have the lamps aout 2' away and while the guitars are quite warm, there has been no damage (yet...)

Sorry to hear you fried yours. I am in a rush to get these guitars ready for a festival next week, so I am going to try to push the drying/curing down to 3 days. I know I'm crazy, but hey I'm on sabbatical so I don't care

I have a pair I use on occasion. 24" minimum, and I do mean minimum clearance at all times.I run mine at 30" away, on a timer with the body or neck rotating on a power carousel. I run the heat lamps in 2 hour on off cycles. I can cure out KTM9 pretty good in 60 hrs of this cycling but there is a high risk of bubbling the finish so till you have done it a time or two keep a close eye the guitar.MichaelP38916.4422222222

Michael, so its like spit roasting a guitar?

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Joe Breault
Merrimack, NH
Perpetual novice

[QUOTE=JBreault] Michael, so its like spit roasting a guitar?[/QUOTE]

pretty much

Not only did I bubble the finish, It also split the top seam apart. I had the lamp set at 2 ft and it was on for approx 30 minutes. I have since switched finishes and decided that patience is a virtue.John How38916.4902893519

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Tickle your guitar daily, and it'll tickle you back.

Thanks Michael, I will keep a close watch and I think you are right about the cycles. I think the stuff crosslinks as it cools.

John, I just heard a little pop and you are right a top seem at the binding opened. I cooled off the guitar glued it back up and backed the lamps to 30".

This is an occasion where I do need to speed it up, otherwise, I agree, it is best to air dry.


Check out what Taylor guitars is doing http://www.taylorguitars.com/global/pdfs/finish_line.pdf

Tomas38916.5313078704

taylor uses uv, not ir.

True Michael, and they also use polyester and not waterborne laquer. Waterborne will not cure faster with uv but IR does speed things up considerably. Like 15 minutes between coats rather than 1 hour. I will be experimenting with spraying two guitars, one curing with IR and the other air curing. I hope to get some data to back up what seems to be

There is no clear published findings other than Michael Payne's above that explore the possibility of controling the speed of the curing process between sprayin and buffing ( a technition at grafted coatings reminded me that KTM-9 continues to get harder as it cures over time)

But the point is, I think it makes sense, searching for ways to get more control over the finishing process. Having better more efficient outcomes with less toxins in the environment and in my lungs.

This is just a personal observation as apposed to any recorded data but I think it is important to mention.

The first guitar I cured with IR lamps I did not rotate during the cure except by hand about every hour on the finial cure out. it appeared to me to have shrunk at different rates over different areas of the guitar. I assumed this was because some areas got more heat exposure than others. So as I refined this process I decided to keep the guitar in constant motion during the heat treating and it seam to get better.

Now with that said, I do not prefer to cure this way. While it does speed up the process it is always a risky process. I am lucky that during the spring, summer and early fall months we have pretty low humidity and high temps here. I have a closet on the Southwest side of my shop that if I close off will get between 95* and 100* with 20-15% or less RH. This seems to cure out KTM9 very well in 7-10 days with out the risk of the IR lamps

Michael,

Thanks for the info. I was wondering, did you use more than one lamp. I have two on stands, one at each end of a little rolling table.

I think I'm getting plenty of coverage without rotating. But I bet it would be much more even rotating as you say. If you don't mind, could you please describe (or post a pic)your carousel?


Thanks,
TE

[QUOTE=Tomas] Michael,

Thanks for the info. I was wondering, did you use more than one lamp. I have two on stands, one at each end of a little rolling table.

I think I'm getting plenty of coverage without rotating. But I bet it would be much more even rotating as you say. If you don't mind, could you please describe (or post a pic)your carousel?


Thanks,
TE [/QUOTE]

Sure. It is real simple! Do you ever remember the aluminum Christmas trees that came with a rotating multi color disc in front of a lamp, well I used a motor off of one of those (a big one, it had a 24" disk. I doubt the small ones would turn the weight) It rotates very slow it takes maybe 15-20 sec to make a 360 revolution. I hung it from the ceiling in my paint room with the shaft pointing towards the floor, I used a 1" wide x 1/8" thick steel flat bar x 18" long with a hole in center to mount to the motor shaft and holes at each end that have deep sea fishing hooks mounted to them. One hook attaches through a hoop on the support bar that is attached to the mortise of the body the other hook attaches through a hole in a block bolted to the neck. I counter balance the bar with small kitchen magnets as needed since the weight distribution changes from guitar to guitar. This is in the center of a 7'x 7' room. I have 2 IR lamps, mounted on one wall. One lamp is at am elevation slightly above the top of the body and one is slightly below.

So in short the guitar is rotating from the ceiling and the lamps are stationary. there is a little more than 30" from the nearest part of a dreadnought guitar to the the lamps.MichaelP38918.5985648148

Has anyone tried this technique with nitro lacquer? Just wondering if it would reduce the wait time for that.

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Dave Rector
Rector Guitars

Dawg gone it, I just threw away my aluminum christmas tree!

I get the idea, thanks for the ideas and info, and for a good laugh (hope you didn't get any fake snow or icicles in your finish)

This is just hack science here, but I figured I'd throw it out there. I knew that year of a chemistry degree would help someday.

The main factor to consider with IR curing, so far as I can tell, is that it heats up the finish. If you're really going for the gusto, the light used should be one such that it heats the finish up more than the other things it's shining on. So, for example, a strong red light will heat up something green more than it heats something red because red objects tend to reflect red light rather than absorbing it.

Every ten degrees Celsius you raise the temperature of a chemical reaction doubles the speed (as a rule of thumb).    Raising the temperature will increase the cure rate on any finish so long as it's not hot enough to melt the finish.

On evaporative finishes, so anything with a solvent, you can also speed up curing with airflow. The more of the solvent is in the air, the slower the finish releases it, so by keeping the air 'clean' (which means dry in the case of water-based) your solvent gasses off faster.



There's actually one other thing, and I'm pretty sure it's the principle behind UV finishes. Some reactions have an 'activation energy' and so nothing happens until this energy is put in, but once it is then the reaction goes on by itself. Think of lighting a sparkler or a stick of dynamite. I'm pretty sure UV finishes work on this principle. IR light tends to heat most everything up, and so it would be much harder to make a finish that   reacted that way to IR (although maybe such a thing exists).

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services