PR Curing Formula

Signed-In Members Don't See This Ad
DurocShark

DurocShark

Member
Joined
Jul 26, 2008
Messages
3,622
Location
Anaheim, CA
I think I've hit the sweet spot on curing and post curing PR.

(This is based on Artstuf and Castin' Craft. YMMV with other brands.)

I've been playing with variations on the amount of MEKP and post cure temps and time to find the easiest to cut, but stable and polishable, PR blanks.

I've gone from over-cooked resin (too brittle) to under-cooked resin (dimensionally unstable) and found what seems to be an ideal combination.

Garage temps during casting process: 50-60*
- 2 drops MEKP per ounce
- Cast in ABS plastic tubes
- After 2 hours, place blanks molds and all in toaster oven at 150* for 30 minutes.
- Let rest overnight

That's it. It cuts super nice and is stable enough for a Pentel pencil using the Pentel stock clip. If it's too soft the barrel will pinch from the clip. These didn't deform at all. But they were a wonder to turn. Hot knife through butter kind of turning.

I just thought I'd share since I was so excited after I was able to reproduce this for several batches with different dyes and Pearl-X.
 
Signed-In Members Don't See This Ad
Don,
Thanks. I have been at about 5-7 drops/oz. I'm waiting to try those pieces soon. Can the MEKP get old in your opinion? I had a small bottle that came with the last can of CC and it really didn't start the cat. process up too much. I ended up with some goop. I got some more MEKP at the big orange box and it seemed to work just fine. Just wondering.
Thanks again for the update.
 
No idea on age of the catalyst. I generally don't keep mine long enough. ;) But I just use enough to kick the reaction, not enough to fully cure. I let the oven do the rest.
 
DurocShark said:
No idea on age of the catalyst. I generally don't keep mine long enough. ;) But I just use enough to kick the reaction, not enough to fully cure. I let the oven do the rest.
Click to expand...

Yeah,
I like the dedicated toaster oven (so does my wife) idea. It has been hot enough here to put it all in the attic +/- 130 degrees for a day or so or on the dashboard of the work truck.
 
Yes, IMHO old MEKP will not kick off the heat procees to set PR.. Gary Max and I have talked about this just this week. He had some old MEKP and it wouldn't set the pr no matter what he did:mad:, using the same gal of pr he used a new bottle of MEKP and all was well in his world again:biggrin:.


cnirenberg said:
Don,
Can the MEKP get old in your opinion? I had a small bottle that came with the last can of CC and it really didn't start the cat. process up too much. I ended up with some goop. I got some more MEKP at the big orange box and it seemed to work just fine. Just wondering.
Thanks again for the update.
Click to expand...
 
Hey Doc...

Very interesting findings. I have been using 6 to 7 per ounce andletting it cure on it's own. I will give this a try.

One question: does the PR release from the ABS tube easily?

Thanks,
Steve
 
ABS molds

Thanks for the above answer. Can you describe the setup of your mold and pouring system? If you don't mind letting out some secrets?

What type of ABS tubes...what size...how do you cap the ends....do you put them in some kind of stand to keep them upright?

Any descriptions or pictures of your pouring station or setup would be awesome!!!

INQUIRING MINDS WANT TO KNOW!!! LOL

Thanks,
Steve
 
I suppose I should do a walkthrough for a basic brewing system.

I use 3/4" ABS plastic pipe in 6" lengths. I use threaded plugs in one end. I use my old q-tip cup to hold 3-4 of these at a time. (I also use 1/2" PVC for blanks I know won't need to be too big.)

In two hours, or whenever I waddle back into the garage after that point, I toss the molds in the toaster oven. I just lay them on the rack. Set the oven to 150* and 30 minutes on the timer and crack open the garage door so fumes don't build up.

I also do the same thing with the resin saver mold from NL88. The silicone isn't bothered by the 150* temp.

My cuttingboard mold died. I killed it by smashing it with a hammer after it leaked all over. heh. So I don't know how UHMW handles 150*, but I suspect it would handle that temp just fine.
 
Definitely do your own experimentation. My 2-stage curing process isn't necessary, it just gives me the best results.

I just thought it might be useful to others.
 
I use about 3-5 drops per OZ and after 20 or 30 minutes pop my Gadget mold in the toaster oven at 150 for 45 minutes it's always worked for me, I like my blanks a bit firmer/harder,
 
bitshird said:
I use about 3-5 drops per OZ and after 20 or 30 minutes pop my Gadget mold in the toaster oven at 150 for 45 minutes it's always worked for me, I like my blanks a bit firmer/harder,
Click to expand...

That's about what I use 3-5 drops depending on the volume. Shallower molds such as a 3/4 x 6 mold will take more. Deeper larger molds such as a slab will take less. The deeper more volume will build up the heat fast. Keep that in mind room temp matters also the colder it is the longer it will take. And if it's hot you could cut back a drop or 2. I usually finish off in an oven just to cure the surface tack.

My 2 cents
 
You must log in or register to reply here.
Back
Top Bottom