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Very spiff!

I would add that you could create a very simple degassing chamber with a mayonaise jar. If you can get a vacuum source to pull 26 hg. or higher, then you can mix the material in a small cup, place it in the jar, and pull a vacuum for five minutes or so. The result will be material that is completely de-gassed when it's poured out.

Also, some two part urethanes are quite a bit clearer than epoxies. These urethanes are called "water clears". With the shore D hardness around 80 or higher they are pretty dang hard but remain very scratch resistant.

http://www.bjbenterprises.com/category.asp?category=8

Look at the WC-780 - 792. You'll probably want the viscocity around 600 cps for what you are doing here. I think if you use this stuff and degassed it....you might like working with it more than epoxy.

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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

When you polish cured epoxy with a wheel and it smudges....it's because the friction drove the surface temperature above the tg .... the "glass transition temperature". Epoxies generally have a set temperature point above which a fully cured piece will become rubbery. It may not necessarily be true of System 3 resins....but for most engineered systems the tg will be higher than the temperture at which it was cured.

So....let your piece cure at room temperature until it apprears stable....about to the point where it takes some effort to leave a fingernail impression. Then finish curing it in the oven at 175F. Two hours ought to do it. Chances are good that the tg will be somewhere over 200F and polishing it will be much easier than if you used a room temperature cure.

_________________
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

For most polyesters, oxygen inhibits the cure...so the material on top that is exposed to the air will never truly cure unless it is deprived of oxygen.

There are two ways to deal with this.

1. Mix in a wax additive called "patch booster" to your polyester resin. Boat guys mix in patch booster when they are fixing local areas. Patch booster migrates to the surface during cure and cuts off the oxygen at the surface. A few polyesters are sold with this additive in it already but most companies that use this additive mix it in themselves wanting control over how it works with their application.

2. Spray a product called pva (polyvinyl alcohol) over the resin after it's applied. This stuff dries pretty quickly when sprayed on and completely seals the surface, allowing for a total cure of the polyester underneath. When the polyester cure is finished the pva coating comes off easily with water. I like using this stuff much better than patch booster. It's a one part system that you can spray on with one of those pre-val sprayers...if it can't be found in an aerosol can.

Both of these things can be found at most fiberglass supply houses or boat shops.

_________________
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

Sorry to be totally off topic, but is this urethane the type of stuff you could use to finish a fretless bass fretboard, to prevent it from string wear? I know that some use epoxy for this, I'm looking for something to this job,

Stefan

No, Stephan. These urethanes are primarily used for casting applications. I will someday attempt to use one these urethanes as a pore fill. Some of these harder resins sand easily and are crystal clear so perhaps they would work well in that way. It's entirely possible that the material could be brushed onto a surface but urethanes designed as finishes will have leveling properties that I wouldn't expect to find in a casting resin.

_________________
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

ok, I've been experimenting with this for a while now and I think I finally have a system that works very well. I'm now using System 3 SB112 epoxy (which you can get from LMII). It cures slower than the zpoxy and has a very high gloss. I'm also using Transtint dyes that I bought from Woodcraft. Start by mixing a small batch of sb112 (50 grams resin/22 grams hardener). Once it is well mixed, pour it out into 2 separate containers. To one, add about 5 drops of "honey amber" transtint dye. to the other add about 3-5 drops of "dark walnut" dye. Other colors are available for experimenting... Once I have my tracings under the shrinkwrap, I take a good artists paintbrush and (using the lighter colored epoxy) paint around the edge of the pickguard, going right up to the line. This thin coating of epoxy will create enough surface tension to prevent the epoxy from running outside the lines. I then use a popsicle stick to spoon some amber epoxy out into the pickguard and spread it out in long lines. I then spoon out some dark epoxy into the open spaces and spread it out to fill in the gaps. Add more epoxy slowly and in small amounts until it flows out up to the lines. You can use a toothpick to trace around the edge and smooth the edges out. This is what the end result will look like. - Good luck and let us know if you try this out... - Justin

Very cool, thank you for the pictorial!

I would be very curious to try this in a mold followed by placement in a hard vacuum. Now I half wish my next project wasn't a solidbody!

Test fit of new pickguard on a new construction

Hey Justin you still around? I wrote you a PM. Please get in touch with me. Thanks.

Wow this stuff is cool, glad this thread was resurrected.

+1 - This is something I have been wanting to try.

Wow, you guy sure like to make work for yourselves. You do know that John (Greven) and I with my BeauGuard cast them to the final shape and with the rounded edges all in one go. No cutting, rounding or buffing necessary. Getting rid of bubbles is also a very simple trick.
Since I learned from him and would need his permission to divulge his methods I'm sorry I can't say how it's done.
-C

_________________
Freeborn Guitars
and home of BeauGuard©

Wow! This is way cool! In a past life I was known as "Yamaha Junkie" The name attracted some 20+ emails a week. The biggest question was "Where do I get a replacement FG300 pickguard?" It was Celluloid with a glue that reacted against it. It seems closer to Saltwater, the more severe the death of the pickguard. I have seen Powder.
Its a ruby red with light brown. Any idea on how to tint close to these colors?

Sooooooo....give him a call and get his permission. You can't just leave us hangin' here......

Indeed. At least give us the bubble trick. I suffer so much trying to drag all 1 million of them out of the pattern before it sets up

Although just the knowledge that there is a trick is helpful. I shall go on a google hunt if you can't say what it is. And if that fails, then I'll just have to run experiments myself.

Hey guys does Easy Cast http://www.bluewhalearts.com/easy-cast/easy-cast-resin work just as well as z-poxy?

Also does anyone have any links to the correct dyes that work best?

John showed us how to do it because for short while we were producing sheets for him. He is a friend and I would never step on his professional turf; hence we do not do a straight tortoise pattern. Since the OP is bragging about ripping off his methods, I have no interest in giving up his and our techniques.
The next time I see him I'll bring it up, and I'm sure we'll laugh about it.
-C

_________________
Freeborn Guitars
and home of BeauGuard©

Hi Chas,
I don't think the OP was "bragging about ripping off Greven's methods", but indeed, gave him a bit of free advertising , by mentioning him as a source for the finished product.
I can understand your reluctance to reveal techniques shown to you by a friend, which he uses to generate income for himself. I am a bit surprised you mentioned they exist at all.
When I share an idea with the forum it is with the hope that some may learn from it, and that some may improve upon it and give that knowledge back to the forum. I like sharing and learning new ways to do things.

Well why bring it up in the first place? Ideas are not unique to any one individual. The wheel would eventually been invented by countless people. Patents are locks on ideas that would eventually come to light. Sharing knowledge is much more powerful then hoarding it. But what ever... Thats for another th4read

In the mean time I don't mind working real hard with a pair of scissors and a sander.

Indeed. But anyway, I found a nice article which describes 3 ways of removing bubbles http://neutron.physics.ucsb.edu/docs/optical%20epoxy/removing_bubbles.pdf
Sounds like heating to 35-40C for 10 minutes is the best for thin pools like pickguards

I messed around with this myself for awhile so I feel your pain. As for getting the bubbles to rise, you will need to be careful about heat as you can get an exothermic reaction going and that creates more suspended gas bubbles. Been there. You can try to degas under vacuum but with the viscosity's I work with, 29hg wouldn't pull them out before we run out of work life of the resin and in some cases made the bubbles worse. You can cut your resin with a thinning agent and the bubbles dissipate wonderfully but the shore hardness values will suffer which effects the buffing qualities. You can run a small bottle torch over the surface rapidly and although it will pop bubbles it is dangerous and creates currents in the resin and messes with your pattern, or you get the resin a little too warm and it exotherms. What I found works for me is a moderate warming of both parts before mix as well as working on a warm heated platen along with gentle mixing. And when the bubbles are on the top but surface tension is too great to release them, load your touch up gun with (in my case alcohol) thinning agent and just mist the surface. Different resin systems will react differently so I adjust accordingly. Just a few thoughts and lessons I learned from the school of hard knocks that sometimes comes at great price.
Rod

Somebody try this, please. With a moderate flame on a bernzomatic propane torch, pass the flame over the surface with a swift, even, sweeping motion. Never hold torch closer than 3 to 4 inches from surface. Sweep past the ends of your work so that the torch never stops on your fresh coating! Avoid over-torching which may scorch the surface. Carbon dioxide rich exhaust gases from a propane flame may effectively release trapped bubbles.

Works with some reactive polymer compounds. Betcha' this is the secret trick.

cheers.

Best to just find a resin set that doesn't have "bubble" problems....

K.I.S.S.

Heating any epoxy will always reduce viscosity but heating will never have as profound an effect as introducing a surfactant into the mix.

Seems to me that any epoxy that can be thinned with denatured alcohol and maintain resonable mechanical properties will accomplish two things with the addition of alcohol. It will eliminate any potential for cracking because the alcohol essentially "rubberizes" the epoxy (the more alcohol [up to 25%] the more rubbery) AND the more alcohol, the more surfactant is introduced...which reduces surface tension and pops bubbles.

Zpoxy and Bob Smith Industries finishing epoxies are basically the exact same stuff in terms of cure times, workability, and sandability. Both thin with DA and produce the same results. The ONLY difference is; Zpoxy has a slight tint and BSI is pretty much water clear.

So....25% alcohol and it will pour like water, be absolutely bubble free in seconds, and be as hard or soft upon cure as the alcohol ratio dictates.

You can let it sit for a while to blow off most of the alcohol and then add the swirly tint dye after 15 or 20 minutes. I'm guessing on the time there....experiment.

_________________
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

The torch trick doesn't heat the mix perceptibly. - Seriously, it's startling to see the results on the polymers that it works on. I'm not sure if it'll work on this particular formulation, but where I've used it it seems like magic. Repeat after 5 minutes or so. It only takes a few seconds to try, and it would leave the mix unchanged. Rubbery epoxy also has the potential for being sticky epoxy, and brushing the surface with the CO2 is so easy. It's been stated that there's an easy trick for this problem, so I'd guess it's worth a try.