OK, it's been over an hour.......

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Monty

Monty

Group Buy Coordinator
Joined
Mar 4, 2005
Messages
8,433
Location
Pearland, Texas, USA.
I picked up some PR from Michael's this afternoon and am attempting to cast some worthless wood. I mixed in the colorant (alumilite coloring), degassed the uncatalized resin in hot water in an ultrasonic cleaner for about 10 minutes, then added the catalyst. It calls for 5 drops per ounce for a 3/4" thick cast. I'm mixing up 8 ounces and added in over 50 drops of catalyst. Placed it in my PP at 40psi. It's been over an hour and it still is the consistencey of syrup (temp in the shop is about 60). So....how long should it take for this to cure???????
 
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If you have a toaster oven that can get down to around 90-100, put it in there for an hour. Or just wait, it will harden soon enough. I found I needed a toaster oven anyway, as they'll be gooey when you get them out, even overnight.

Dale
 
If you don't have a toaster oven, a little space heater and a cardboard box will warm up enough to set pr for you. BUT, be carefull to use a big enough box that it don't catch on fire. Even then, I would put it out somewhere safe, just in case. DAMHIKT A second alternative is to use an ice chest and a lamp with an incandescent bulb. Just don't use the wife's good one, as it will smell like PR till doomsday. Again, DAMHIKT :)
 
i've had luck with a toaster oven....set at 150, and doing the 15 minute timer a couple two or three times.....then let it cool and it's hardened.....
i agree, 60 degrees is a fight.....but with 8 ounces...i don't use more than 35 drops....and within 3 hours, it's still very sticky but then that's why i bought a cheepy toaster oven...just for that
 
If you have a non-return valve on your pot, why not just do all the smelly stuff in your shop, pressurise it and then take it into the house where it's warmer?
 
Mannie, I've been using an oven on all my PR for well over a year now. I bought a thermostically controlled oven at goodwill that looked new for $20.
I preheat the oven to 150 degrees and before adding the activator I place the PR in the oven for 30 min to an hour according to how cold the shop is, this thins the PR making it flow into cactus, worthless wood etc much better and also will set quicker as what the activator does is heat the pr. I then place it in my pot for at most an hour or 2 as once it jells 30-40 pounds of pressure won't do any more to the PR.
Now at this point I place it back in the oven for 30 to 60 minuets and they are ready to turn and completely dry.
 
skiprat said:
If you have a non-return valve on your pot, why not just do all the smelly stuff in your shop, pressurise it and then take it into the house where it's warmer?
Click to expand...
This is what I did, and when I opened the pot, it still hadn't hardened, about the consistency of syrup.



OKLAHOMAN said:
Mannie, I've been using an oven on all my PR for well over a year now. I bought a thermostically controlled oven at goodwill that looked new for $20.
I preheat the oven to 150 degrees and before adding the activator I place the PR in the oven for 30 min to an hour according to how cold the shop is, this thins the PR making it flow into cactus, worthless wood etc much better and also will set quicker as what the activator does is heat the pr. I then place it in my pot for at most an hour or 2 as once it jells 30-40 pounds of pressure won't do any more to the PR.
Now at this point I place it back in the oven for 30 to 60 minuets and they are ready to turn and completely dry.
Click to expand...
Guess this gives me another reason to get the oven I picked up from the neighbors trash pile for PC,ing hooked up behind the shop.
 
Well...the truth finally comes out

After "cooking" in the toaster oven for about an hour at between 150-200, it finally hardened. Popped out of the mold but too hot to do anything with yet. Guess it will wait until tomorrow.
 
Mannie,

Just remember, PR is very flammable. If you don't think a toaster oven can be a problem, listen to this little story.

I was doing some stabilizing with plexi disolved in acetone. I had just taken a batch out and wanted to speed up the drying a little. I place about 16 1/2 blanks in the toaster oven on about 130 and went back to turning something. About 20 minutes later I hear a deep but not loud "boom". I turned around and my toaser overn was fully engulfed in flames sitting on my work bench! Grabbed the fire extinguiser and put it right out but it did teach me a lesson.
 
MesquiteMan said:
Mannie,

Just remember, PR is very flammable. If you don't think a toaster oven can be a problem, listen to this little story.

I was doing some stabilizing with plexi disolved in acetone. I had just taken a batch out and wanted to speed up the drying a little. I place about 16 1/2 blanks in the toaster oven on about 130 and went back to turning something. About 20 minutes later I hear a deep but not loud "boom". I turned around and my toaser overn was fully engulfed in flames sitting on my work bench! Grabbed the fire extinguiser and put it right out but it did teach me a lesson.
Click to expand...
Curtis,
That's why I set it up outside on the BBQ grill.
I would venture a guess that the main reason yours caught fire was because of the acetone flashing off.
 
contact workinforwood, he's got the process down on illuminite.


Monty said:
I picked up some PR from Michael's this afternoon and am attempting to cast some worthless wood. I mixed in the colorant (alumilite coloring), degassed the uncatalized resin in hot water in an ultrasonic cleaner for about 10 minutes, then added the catalyst. It calls for 5 drops per ounce for a 3/4" thick cast. I'm mixing up 8 ounces and added in over 50 drops of catalyst. Placed it in my PP at 40psi. It's been over an hour and it still is the consistencey of syrup (temp in the shop is about 60). So....how long should it take for this to cure???????
Click to expand...
 
Curtis, while I do agree that PR is flammable, I believe that keeping it at or below 150 degrees is no more danagrous than storeing it in a garage that at times in summer can reach well over 100 degrees. Of coures we need to watch when artifically heating any flammable and not leave but IMHO we are more at risk cutting ourself in the shop.



MesquiteMan said:
Mannie,

Just remember, PR is very flammable. If you don't think a toaster oven can be a problem, listen to this little story.

I was doing some stabilizing with plexi disolved in acetone. I had just taken a batch out and wanted to speed up the drying a little. I place about 16 1/2 blanks in the toaster oven on about 130 and went back to turning something. About 20 minutes later I hear a deep but not loud "boom". I turned around and my toaser overn was fully engulfed in flames sitting on my work bench! Grabbed the fire extinguiser and put it right out but it did teach me a lesson.
Click to expand...
 
I could be wrong, but 200 seems a bit hot and it is unnecessary. I've been at about 100-120 and it's fine. If it's so hot you can't handle it it could crack, because it's undergoing exotherm as it is. I don't remember if you said you added anything to it, like cereal or pasta or even Pearl-X. That could slow it down too, although 60 degrees is pretty cool.

Anyway, I am NO pro at this, and trial and error will either become your best friend, or you won't be doing this long. I wish there was a good book out there, but then again there are so many variables to this it probably wouldn't do any good.

Have Fun!!!

Dale
 
I looked it up. Acetone has a very low flash point of -4 F according to a MSDS I found! PR is quite a bit better at 88 F. I believe, (but am not chemist by any means, just a dumb ole builder:)) the the flash point they are referring to is when the material begins to "evaporate".

Edit in: Actually, here is a definition of "Flash Point" I found on Wikipedia: The flash point of a flammable liquid is the lowest temperatur at which it can form an ignitable mixture in air.
 
maxwell_smart007 said:
Quote: At temperatures greater than acetone's flash point of −20 °C (−4 °F), air mixtures of between 2.5% and 12.8% acetone, by volume, may explode or cause a flash fire.
Click to expand...

It sure will!:biggrin::biggrin: Another reason to always have a fire extinguisher in your shop where you can get to it quickly!
 
maxwell_smart007 said:
60F is too cold to cast? Man, I couldn't even cast in my house right now - we keep it at 58F because we have no insulation in the walls, and it's -20C outside...costs too much to heat otherwise...
Click to expand...

Rcommended minimum temp for Silmar 41 is 72F. However, you can add up to 50% more MEKp to compensate for low temperature. As with everything you need to experiment, take notes and or make a temp, volume, time chart.

Your PR may have a different working temp range than S41. Refer to instructions that accompanied your resin.
 
There's still time to use the 20% alumilite coupon in the vender section this month only! 60 degree's, no problem...I poured it at 40 degrees and it was totally set in 4 hrs, drilled and tubed it! So much less hassle..no toaster ovens, no figuring out how many drops of anything to add. You better hurry.
 
You still should use a toaster oven to post-cure poly-eurethane resins. Poly-eurethanes also have minimum working temps, check the accompanying literature. According to the call I placed to Alumilite, Alumilite Clear's working temp is 70F or more, otherwise you can cause "temperature induced cure inhibition".

For PR's you don't have to count drops. You can calculate 1% by volume and use a syringe to dispense your MEKp, or you can use a scale and go by weight. The Specific Gravity of MEKp is 1.15, so in small batches of PR of you can go by 1%. I personally like 0.5% by volume (measured in metric ounces)
 
Glass Scratcher said:
You still should use a toaster oven to post-cure poly-eurethane resins. Poly-eurethanes also have minimum working temps, check the accompanying literature. According to the call I placed to Alumilite, Alumilite Clear's working temp is 70F or more, otherwise you can cause "temperature induced cure inhibition".

For PR's you don't have to count drops. You can calculate 1% by volume and use a syringe to dispense your MEKp, or you can use a scale and go by weight. The Specific Gravity of MEKp is 1.15, so in small batches of PR of you can go by 1%. I personally like 0.5% by volume (measured in metric ounces)
Click to expand...

Interesting. .I asked them one time when I was over there about temp, and they said heat the mold and all will be great. So that's all I do. Even with the heat on, it is never 70 in my shop..that's too expensive! 60-64 is plenty warm, especially when you are working on things. I think thickness is a factor too. The thicker your pour, the more natural heat happens from the chemical reaction.
 
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