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Cat-Urethane question
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=12964		 Page 1 of 1
Author:  old man [ Wed Jul 25, 2007 2:12 pm ]
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A quick question, please, for those who use catalized urethane or, if you don't know and you send your geetars to Tony, maybe you could ask him this:

Is the stuff being used on guitars the same that is used by many auto body men, or is there a special formulation for wood?

Ron
Author:  old man [ Wed Jul 25, 2007 2:39 pm ]
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No, Hesh, I can't afford Tony at this time. My brother is a paint & body spray wizard and he uses cat-urethane. I'm going to let him try finishing one for me, but I just need to know if his car stuff is the same as Tony uses.

Ron
Author:  old man [ Wed Jul 25, 2007 2:47 pm ]
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You're a prince, Hesh, many thanks!!

Ron
Author:  Tim McKnight [ Thu Jul 26, 2007 12:11 am ]
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According to McFaddens it is not the same formulation. It has more plasticizers in it to allow for wood movement. Even though steel moves on autos it isn't nearly as much as wood.

It does spray about the same though. It builds MUCH faster than Nitro or waterborne finshes so you have to be mindful of how much you lay down.
Author:  old man [ Thu Jul 26, 2007 1:12 am ]
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[QUOTE=Tim McKnight] According to McFaddens it is not the same formulation. It has more plasticizers in it to allow for wood movement. Even though steel moves on autos it isn't nearly as much as wood.

It does spray about the same though. It builds MUCH faster than Nitro or waterborne finshes so you have to be mindful of how much you lay down.[/QUOTE]



Tim, do you have a web address for this product? Also, from reading on your site, it appears that you do the normal pore filling and sealing with shellac before using the urethane. Please confirm this for me, and do you lay down any other kind of primer or sealer for the urethane?

Thanks,
Ron
Author:  joe white(old) [ Thu Jul 26, 2007 3:12 am ]
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I think that it just might be possible that many urethane clear coats might be very similar. Clearcoats can be high and low in solids. A single clearcoat can be catalyzed with many different catalysts ( specifically designed for that clearcoat) in order to alter the actual application of that single clearcoat. Clearcoats can also be used for purposes other than their intended or warrantied purpose. These applications may or may not be supported with a waranty by the paint manufacturer if they are applied on surfaces that the manufacturer did not intend or design them to applied on. The warranty or guarantee of the product would then fall entirely on the hands of the applicator or user of the product. So, with all that jibberish we come to this. Any clear can be put on anything, if it sticks. Whether it sticks or not depends on how the surface is prepared and how stable the surface is. How the surface is prepared depends on the user of the clear. Noone wants a product failure and I am sure that if someone is putting automotive clear or wood clear on a guitar they have researched it enough to know it's performance or limitations.  
Author:  Tim McKnight [ Thu Jul 26, 2007 3:41 am ]
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Ron, Please send me an email as a reminder. I have my spray schedule, with part numbers, that I can send to you.

I typically pore fill funky colored woods with Z-Poxy over bare wood. EIR and Mahogany is sometimes sealed with paste filler or Z-poxy depending on my mood and the color I want to achieve. The tops are always sealed with Shellac. Filler is allowed to dry for two days minimum. Then I shoot urethane directly over the filler, shellac or Z-poxy unless it is an oily rosewood. Then I shoot two coats of McFaddens rosewood sealer mixed 5/1 with hardener at 1 hr intervals. Then three coats of Urethane at 1.5 hour intervals on day one. Wait two days, level sand, shoot two coats on the top and three on the B&S. Wait two weeks, sand to 2000 and buff. I have buffed in 2-3 days but you can expect some shrink back if you push it this fast. I just wait two weeks and shrinkage is not a problem.
Author:  Daniel M [ Thu Jul 26, 2007 3:46 am ]
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I use a product called Acroma. It is a three part system with a sealer, base & topcoat. It is formulated for use on wood.
The sealer coat is designed to improve adhesion on oily wood. Works great on greasy old Cocobolo. I use the sealer on all my instruments because it pops the grain really nicely.
I have used auto finishes in the past (aircraft finishing) & it feels brittle compared with the stuff I'm using on instruments.
The only problem with the three different coatings is that sand-throughs show. Otherwise its a very forgiving system... And... No pore filling required!
Author:  Rick Turner [ Thu Jul 26, 2007 5:21 am ]
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As Tim knows, there are few companies that do as much finish formulation specifically for guitar use as does Lawrence McFadden. They don't have much of a web presence, but you can call them in Philadelphia and talk to Peter Beck, an application engineer. Peter came to the last NAM show and saw a lot of his customers, big and small. They supply us, SCGC, Mike Baranik, Addam Stark, Fender, Tacoma, Taylor, etc., etc.

Don't cut corners or cheap out on finish materials; it is not worth it.
Author:  joe white(old) [ Thu Jul 26, 2007 1:45 pm ]
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It almost seems like McFadden doesn't like to communicate with small time (independent, one at a time) builders/finishers. They acted a bit condescending when I spoke with them early this spring. Maybe they were just busy with large scale builders that day? I wanted to learn more info about their UV coatings. I guess I can understand it though. Their big accounts like Taylor prolly buy clear by the container load (very large tubs) and I'm kicking around trying a quart or maaaaaaybe a gallon. I ended up learning more about McFaddens UV stuff from Tom Anderson. Sometimes you can learn more from the "end users". 
Author:  Tim McKnight [ Fri Jul 27, 2007 12:50 am ]
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Joe,
You bring up a valid point. McFaddens is a large company and I am sure they do cater to larger accounts. I have always been treated very hospitably whenever I have called and asked questions so you may have just caught someone having a bad day (we all have them upon occasions).

McFadden's does have a minimum order amount so y'all need to be aware of that before you call and they only deal with companies or professional builders. I purchase my Urethane in 5 gallon cans (minimum). It is a wonderful product, not perfect, but one of which I have grown to really like and appreciate. It isn't cheap (>$500 + a HASMAT fee) a can but since it builds much faster I can get tripple the amount of guitars out of it than a similar sized can of nitro. It does have a shelf life of 6-12 months so if you can't use 5 gallons in that amount of time then this may not be your best choice of finish. Yes, it is higher priced than nitro but I think it is a superior finish in many ways BUT this is just MHO.

UV is VERY expensive to get into. The learning curve can be long and tough (Kevin G, Kevin R, Tom D, Jim O, etc...) The product is about the same price as Urethane but the cure lights are very pricy and HEAVY. You need a dedicated booth and speciall PPE. A hand held unit will cost you $2500 - $3000. Better yet is an automated oven starting around $15K. It isn't a perfect finish by no means but it has a LOT of advantages, namely TIME. You can spray, cure and then buff in a matter of minutes. It is geared more towards a luthier / small scale shops who are cranking out 50 or more instruments a year. It just is too cost prohibitive to get into for the small scale builder, IMHO.
Author:  Rick Turner [ Fri Jul 27, 2007 3:37 am ]
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The real advantage to UV cure is not the speed of the cure...that's nice and it's certainly razzle-dazzle...but the real deal is that with UV you don't have to mix the finish; it can sit in a pressure pot or even be pumped from a 55 gallon drum.   It's pre-thinned, it's got the Ciba Chemicals UV initiator in it, and it comes to the gun in a pressurize hose. You don't have to mix chemicals, you don't have to deal with a lot of gun clean-up.   

The speed of cure is cool, but until you're making 50 guitars a day, there isn't a huge advantage over chemical curing (MEKP) where you can cure and rub out in 24 to 48 hours if you like.

By going to the 3M Paint Preparation System, I feel I've sort of bridged the gap between the pain in the butt of using a normal HVLP setup and going to pressure pot UV with polyester.   The 3M sustem uses disposable plastic paint cup liners and I can mix enough poly to shoot a coat on about 8 instruments at a time.   I don't have to clean my gun out but once a week...I just run acetone through it after I'm done spraying.   They have adapters to go with just about any spray gun. I use a SATA NR-95.
I'm shooting about 30 instruments a month like this, and see little reason to spend the bucks on UV at this time.

It was Bob Taylor who convinced me that UV wasn't right for my application.
Author:  John Mayes [ Fri Jul 27, 2007 3:53 am ]
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McFaddens Cat urethane (chemical cure not UV) is more like a lacquer to me
than some other urethanes (like those used in the automotive industry) I
can't quite put my finger on what it is though about it. I've not worked with
the UV cured stuff though (we use it here at McPhersons, but I don't work in
that department)

I liked the Cat urethane though and it was vastly superior in application to
me, and it was easier to get a nice thin coat than nitro.
Author:  joe white(old) [ Fri Jul 27, 2007 7:36 am ]
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[QUOTE=Rick Turner]
It was Bob Taylor who convinced me that UV wasn't right for my application. [/QUOTE]


YEP! For me it was Tom A. that convinced me to not pursue the UV for now. Establish a market with cat-urethane and respond to demand as it occurs. Sound advice!
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