Official Luthiers Forum!

Yesterday I received the e-flyer from RC Tonewoods and followed this suggested link:

http://www.mimf.com/cgi-bin/WebX?50@61.UhU2atEKGXa.1@.2cb6d33b

to a thread on the MMIF giving an overview of finishing options. There you can find a comment from Mario saying two things:

1) A catylized polyester finish can cure in less than 24 hrs, and,
2) It can be applied with a brush.

If this is true, I wouldn't mind doing some experimenting. Can anyone recommend what kind of polyester finish I should buy and what other "ingredients" I would need, if any?

Thanks,
Pat

PS I know there must be some reason this isn't easy, otherwise I assume a lot more people would be doing it.

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

I haven't brushed polyester, but it does cure really quick. It's possible to go from spray to buff in 24 hours. I suppose it could be brushed, but I'd bet brush marks would be a problem. It's pretty hard to sand too. I haven't used any Polyester since I've ran out of Mcfaddens. I believe Mario uses reslack, from Chemcraft. I haven't looked into different brands. I'm not really a fan of polyester finishes, but like always opinions vary.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

These are my notes on Mario's process as described here a few years ago in the "Lacquer vs. poly" thread.

As someone who sanded a polyester coating off the top of a guitar (the coating was badly damaged), I can assure you will spend long hours sanding it. Never again!

James, what happens if they get near each other?

Mike

At the mimf link from the OP, Mario says that catalyzed polyester "sands like a dream." Did you use the identical products that Mario did? Maybe he has a way of applying very smooth?

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"...you have to get over your strict adherence to your largely imagined notion of absolute perfection..."

Thanks for the info guys. Turns out that I pass by Chemcraft fairly regularly when I drive from Ottawa to Toronto. Hopefully it can work out soon that I can stop in and see if I can't get a little batch of polyester to try out. If I do, I let you know how it goes.

Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Mike, I don't know the specifics, but they react badly to each other.

Mixing MEKP (I call it peroxide, but it's not what you bleach your hair with) with cobalt can cause a violet, quick fire. MEKP is dangerous stuff. Skin contact is very dangerous. If you get a drop or splash in your eyes you'll be blind. If you ingest any it will kill you. I would recommend wearing a tyvek suit and a hooded respirator(complete with face mask) even if brushing it. Polyester, (and most other catalyzed finishes) is inteded for use by professionals, in a professional enviroment, with proper saftey equipment. Educate and protect yourself reguardless of your finish choice. Just because your using a brush doesn't mean you can't hurt yourself.

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

The danger of MEKP is well overstated here. Statements like this can easily drive people away from potential solutions to their problems....so every time I hear this kind of inflated reaction to chemicals I'm going to repost the following story:

I've been working with MEKP (a catalyst for polyester "gel coat" - which all fiberglass boats are finished with), epoxies, and urethanes for nearly 20 years. The State of Washington sent two guys out from the Dept. of Labor and Industries with sensors to hang on my employees. In our shop, at that time, gel coat was sprayed ino the OPEN AIR WITH NO SPRAY BOOTH. The only ventilation was a large open door on one side of the building. After several full shifts, the STATE OF WASHINGTON (read that to mean "liberal nanny state" if you are inclined) determined that my employees should be on a VOLUNTARY respirator program.

Logical point: The paternal State of Washington says it's UP TO EACH EMPLOYEE whether or not they wear a respirator around moderate exposure to all these chemicals. How does one reconcile that point of fact against this post or any other post revealing a visceral fear of chemicals? MEKP is not nearly as toxic as woody's post implies. All these chemicals are highly regulated. Read and follow the MSDS. It tells you what you need to know about the chemicals you are working with. There is a WHOLE INDUSTRY of competent people behind the creation of these documents.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

My tyvek suit was only a few dollars. Better to be safe than sorry. When Rick and Mario were initially writing about this, they each suggested full suits with eye protection and respirators.

The only incorrect "statements" in this thread are made by someone who thinks spraying gel coat with a spray system that mixes the chemicals at the tip is the same thing as mixing them by hand.

Zlurgh (or whatever your name is) if MEKP isn't dangerous drink some, or splash some in your eyes.

_________________
I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Woody, I endorse your point of view, and I sympathize with the tone of your last post. Nevertheless, we'll have a clearer discussion if we keep the level down a little bit. As your tag line points out, this isn't a contest. I think what you mean to say to Zblurgh is "I stand by my previous comments."

Let's not get anything toxic on us.

_________________
Tim Allen
"Never hurry, never rest."

Zlurgh:

Please don't impede a cautious attitude towards a dangerous chemical.

What you describe squares with what one would expect. Safe practice in using something by definition renders its use safe. Obviously the kind of exposure in your description is not of exceptional concern. You simply are not describing conditions or use of MEKP that is indeed very dangerous. I.e.: a sufficient splash of concentrated MEKP in the eye will destroy that eye in seconds. The story I always bust out is one I read in Fine Woodworking many years ago of the guy whose shop was 60 yards away from running water. Mixing a batch of fiberglass resin by hand, he got a good splash of MEKP in one eye. By the time he got to the house where the sink was to try and wash it out, that eye was an irretrievably shrivelled brown ball. I've read at least one other similar account.

Handy squirt bottles - eye dropper bottles even! - of MEKP sit on the shelf at my local hardware store and marine shop in easy reach. It's labelled with exactly the same safety warnings as the resin its used for and all the other stuff it sits next to, even though none of that will hurt you the same way. A lot of people don't realize it's not MEK. I indeed find it a little spooky. This is not a "...visceral fear of chemicals..." but a very rational caution about a specific chemical.

Peace,
Sanaka

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...imagine there were no hypothetical situations...

FWIW, when I was working with the stuff, I had dedicated glass syringes for both the cobalt and MEKP. They just reinforced safe use and made everything easy to mix. You cobalt the stuff and let it sit, then add the MEKP when you're ready to roll.

What is cobalt? Isn't it a metal? how do you spray or mix metal?

_________________
Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

You assume we used gun that mixes at the tip....but we mixed it by hand. We made composite propellers. Each blade was made seperately and then combined in set of two, three, four, or five in an aluminum hub....which means they HAD to balance as a unit. That forced us to accurately weigh the gel coat and catalyst for each blade prior to spraying. We were in business many years and made about 20,000 propellers which means we made about 80,000 blades....which means we mixed MEKP into gel coat about 80,000 times.....by hand. Although we provided full protective measures, our employees were given the option of using them by the State of Washington. I am certain that MEKP ended up in eyes and was ingested as a result. Nobody died. Nobody went blind.

You said ingesting it will kill you and the getting it in your eyes will make you go blind.....but that's NOT what the MSDS says....that's not what my experience says....and that's not what the State of Washington's regulatory policies reflect.



The MSDS doesn't say it's ok to drink. Maybe you could acknowledge my point? Be as cautious as the MSDS says to be...but when the danger of a chemical is overstated it does a disservice to those who might find it useful. Of course this makes the point that everyone should be informed by the MSDS of the product they are using.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I don't. That's your inference. I advocate adhering to the safety instructions given in the MSDS....which advises caution.

"If you get a drop or splash in your eyes you'll be blind....If you ingest any it will kill you".

That statement is quite exaggerated.

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

what Tai fu asked?

Zlurgh wrote, in part:

I don't know that it's inference so much as just what I feel about your statements. Granted some others' statements were, technically, exaggerated (will be blind, will die as opposed to might be plus almost certainly will be injured and in pain...)

Google kicked this up from one MSDS:

And from another MSDS:

Zlurgh, your shop never had an incident. Your safety protocols were obviously effective. What exactly were your safety precautions for mixing?

Peace,
Sanaka

_________________
...imagine there were no hypothetical situations...

I don't know really anything about how they work, but cobalt dryer and Japan dryer are liquid products added to some paints and finishes to speed drying, I think by encouraging oxidation. They are "salts" of metals (like cobalt). These are presumably soluble in some liquid solvent that is miscible with the finish. I have no idea if this is the same stuff used in a catalyzed poly resin, and presumably the specific action is very different than in a traditional varnish or paint. So, uh, yah, hopefully this non-information has been entertaining...

Peace,
Sanaka

_________________
...imagine there were no hypothetical situations...