Various consistencies of Poly Resin?

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spiritwoodturner

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I've finished several batches of PR, under some different circumstances with different equipment, and here's my question. Are there different cutting characteristics with PR, depending how much catalyst you add, what you add into the finished mix (beans, rice, rutabaga's, whatever), how you mix it, etc.? My first few batches have turned more like the PR blanks you buy that act more like glass than plastic. I always use sharp tools, and I've gotten them done, but what about the PR blanks one buys where you get nice ribbons off the tool, that are more "rubbery" in consistency than what I'm getting. Then again, are those resin at all, or are they Acrylic Acetate or something like that?

The reason I ask, is I was cutting a tenon for a Silver Bullet today and even with a freshly sharpened 1/16th" parting tool I got a little piece crack off like glass. I find the other blanks I'm referring to above don't tend to do that. Does Alumilite offer that more rubbery consistency?

I did get a perfect fruity pebbles Dick Sing pen done this weekend, will post pics when I get out of the shop long enough to take them. My kids want me to make one for every single kid in both their classes. I also did my first batch with an untrasonic jewelry cleaner like the one Don Ward was referring too in a recent thread. I was a bit skeptical about their ability to actually mix material, but as I watched it you could actually see it turn it over, like a mixer would! NOT a good option if you are trying to keep colors separate, but the mold was VERY HOT to the touch when I took it out, and was hard and dry in an hour, I'm sure due to the warm water bath and better mixing than I was getting, even with a drill and tongue depressor. The reason I set this batch in the cleaner was to see if I got no bubbles in the mix, because until I get my 2nd pressure pot set up (I have buckeye burl stabilizing right now) I wanted to know if this was a good alternative. But a second pot is imperative. And a third. And...

On a side note-Don't use the clear/colored plastic cups from Costco to hold resin in while mixing in the ultrasonic cleaner, or I guess for anything. The resin MELTED the bottoms out of both cups while they were in the water bath! I got it cleaned out with Acetone, but don't make that mistake, now that I have...there is a lot to learn about this casting business, but it is FUN!!!

Back to the Laboratory,

Dale
 
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rdunn12

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Too much catalyst will make PR brittle.I have never had PR dry in an hour.(not even in the summer,shop 80 degrees or so)How much catalyst are you using per ounce?
 
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spiritwoodturner

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3 drops per ounce. My 1st batch I used 5 per ounce, but thought I'd back off, and it cured hot and fast! I really do think using that ultrasonic cleaner had a lot to do with it-it mix it like I couldn't by hand, by any means.

I haven't turned this yet, but I'm keeping a journal and will repost back about the qualities of this mix.

Thanks for asking,
Dale
 

rdunn12

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Well,that shoots down the too much catalyst theory because that is about the same thing I do.And mine does'nt dry anywhere near that fast.I would like to know what you find out in your playing if you don't mind.
 
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spiritwoodturner

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Ronald, I not only don't mind, I learn by sharing, so of course I will.

I'm brand new at this, have only done 3 batches total, and this one came out so hot you could hardly touch it, with 3 drops per ounce!!! Have you used an ultrasonic cleaner yet? I'm curious what Don Ward has to say about this. My feeling is that thing mixes the stuff almost on a molecular basis, or it just plain mixes the crap out of it!

I'll keep the board posted,

Dale
 

rdunn12

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I have been through five gallons of PR.No,I have'nt used the Ultrasonic cleaner.I just set mine on the drill press and turn it on.Then on to the PP.Works for me.I did some pine cone casts a couple of days ago.Turned 1 and had 1 air bubble so not bad really.And it was small.I am curious as to why yours is drying so fast compared to mine with the same amount of catalyst.It must be something to do with the ultrasonic thingy.:biggrin: I have added up to 10 drops of catalyst per ounce and got what you are talking about.An almost glass hard blank.But,it still does'nt dry that fast.Not for me anyway.I also casted a top for a peppermill 3 inches in diameter and 3 inches tall.Without thinking I added ten drops per ounce and it was cracked right out of the mold.The mold was extremely hot and the PR was obviously brittle.
 
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What PR are you using? How big are your drops of MEKp? Was the MEKp provided by the manufacturer of your resin or did you buy it separately? MEKp comes in different strengths and can affect reaction time. The seller of your particular product should stock and supply the recommended MEKp, but they don't always.

What percentage of additives are you putting in your PR. Laminating resins (Silmar 41)can take from 5%-10% of additions. Swing resins can take from 50%-70%.

Are you superheating your molds before casting? You really only need to get them warm.

How warm is your shop? How old is your PR? What is the ambient temperature at which you are casting?
 
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rherrell

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How MUCH PR has ALOT to do with it. 16 ounces of PR at 3 drops per ounce will cure alot faster than 3 ounces at 3 drops per ounce.
 
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spiritwoodturner

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Charles, I've been getting the Michael's stuff, with their hardener. I read with interest your back and forth with Don about weight. I may try that, but man this is getting expensive! Anyway, maybe the drops out of their bottle are too big. I'll try less and less until I get it set but not hot. I'm using 3 drops per ounce, and I used an ultrasonic cleaner with a warm water bath like you and Don were talking about. The water is hardly hot, so don't think that's what gave me the kind of heat I ended up with.

My shop is a comfy 65 year round, thanks to a lovely gas stove with glowing embers! I sit in front of it while doing my pyrography.

Rick, that's interesting. It flies in the face of logic but I'm sure logic doesn't always work with this stuff! That's why I'm asking, you guys know from making most of the mistakes what works. Don't know how often I'll be doing 16 oz. at a time, but I'll try larger pours.

Thanks so much to all,
Dale

UPDATE: I just cut and drilled the batch that got so hot and cured so fast. It did both like butter! Nice, long strings off the saw and long, curly twists off the drill. I just did epoxy the tubes in, but my guess is these are going to turn just like I want them too. I'll turn them tomorrow and report.
 
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If you are buying the Cast'n Craft PR from Michaels it could be old. Resin is pre-promoted so that it has a limited shelf life (liability issues). The older it is the faster it will accelerate when you add the catalyst.

If you are going to buy from Michaels ask them if they can tell you if they have date codes on their pricetags. Some stores do, and if they do, then you can buy the freshest PR they have.
 

its_virgil

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I was told by one manufacturer that polyester resin has shelf life of 6 months from the time of manufacture. I've had a couple of gallons that were not totally used for almost a year and the last 3 inches in the can worked fine...Others report differently. A friend gave me an unopened gallon that was well over a year old and it worked fine also. Both were Silmar 41.

When I first started casting I used several types of coloring or tints. I used India Ink:), universal tints from paint store:mad:, acrylic paint:mad:, acrylic pigment:biggrin::mad:, Mixol:biggrin:, pigments from resin suppliers:biggrin::frown:, and resin pigments from hobby stores for resin:biggrin:. Pigments sold by the resin suppliers come in paste, powder, and liquid. It doesn't take much and can be overdone and affect the cure time. India ink is not as dense as pigments and worked best with pearl powder. Pearl products are also available in liquid and some pigments have pearl mixed in. I really like the pearl powder. I would suggest to stay with tints and pigments sold by resin dealers. I also experienced some colors not curing as quickly. I wish I had taken better notes. I only seriousoly cast snake, labels, and other clear castings now and my experience with tints and colors has moved to the back.

I use Silmar 41 and the resin sold by Composites One which they call Swing resin. I'm not sure what the difference is. They smell the same but I like the Swing resin better...Roy and I have talked about this and I think he agrees. I also experienced better results with the Swing resin when using colors and tints...it seemed to cure more consistently.

I use 3 drops per ounce. I use an ultrasonic cleaner with the heat turned on and zap it for about 30 minutes or longer as I prepare the blanks for casting. I've not measured the temp but I'm guessing the temp is close to 150-170 degrees. I do not heat the molds. My shop has HVAC but I rarely have it warmer than 65 or so this time of year. I have stopped using vacuum. I pressure cast at 30 psi. I usually cast in the evening and leave the casting in the pressure pot overnight. Saturday I made several casts and took them out after 4 hours and started the next cast and they were completely cured, hard, and not sticky. I could have turned them then. If the casts seem to be not totally hard or are sticky on the exposed surface, I put them on the window sill in the sun or outside in the sun and they are fine after a few hours.

Terrf Hefner, aka td here on IAP uses Mixol colors, I think, and has great results. Woodcraft has a Mixol kit on sale or clearance now.

I'll add more as I think of more.
Do a good turn daily!
Don
 
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I used mixol yesterday and its a vibrant pigment,$5 a 20ml bottle at wood craft.I'm new so have very little casting under my belt,so take my info.as a newbies info.LOL.I have stuff coming out of molds today,fingers crossed.Victor
 
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I was told by one manufacturer that polyester resin has shelf life of 6 months from the time of manufacture. I've had a couple of gallons that were not totally used for almost a year and the last 3 inches in the can worked fine...Others report differently. A friend gave me an unopened gallon that was well over a year old and it worked fine also. Both were Silmar 41.

snippage

Terry Hefner, aka td here on IAP uses Mixol colors, I think, and has great results. Woodcraft has a Mixol kit on sale or clearance now.

I'll add more as I think of more.
Do a good turn daily!
Don


Yes, you are right, the real world shelf life depends on storage. If you store the resin against a southern facing exterior wall in an unairconditioned garage throughout the summer, chances are you will be gelling in 5 minutes...

One of several reasons why the manufacturer makes PR to self-promote is that they are concerned with the liability of being blamed for a house fire.

I wouldn't know about the resin promoting out though, I seem to go through my 5 gal buckets too fast.
 
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