First time pour with Silmar 41 - Too old? User error?

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sjmilone

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Sep 26, 2014
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Got my hands on an unopened gallon of resin with activator. It's been sitting at room temp for over a year. Is it possible that it is past its useful life but still flows as liquid?

== Environment ==
With mixing cups sitting on top of a warm-to-the-touch toaster oven, ~74° shop temp, low humidity.

== What I did ==
Poured (7) two-ounce cups, one-each with "smaller than pinky fingernail" amounts of pearlEX powder, glow in dark powder, holographic metalflake, and a proprietary test additive.

Mixed each well & added MEKP, 5 drops per ounce (10 per cup) in sequence, mixed each well. No apparent change after 30, 45, 60 min with occasional stirring to keep particles suspended.

== What happened ==
Added a few more drops MEKP, mixed, heated a few minutes at 150°, couldn't tell any difference. Raised temp a bit (180°, I think?) and it went from liquid straight to gel in those two minutes.

== Questions ==
Is it just a case of an impatient user?

Is it possible the product is old and just slow to react?

Would preheating the uncatalyzed resin help? Water bath or a couple minutes at 150° in the oven?

What consistency am I looking for, (for a good balance of particle suspension vs distinct color separation) to pull the trigger and start pouring...and not end up with cups full of semi solid gel?

I mean I could just pour and set it in the pressure pot (or on the counter) as soon as it's mixed well with the MEKP, and just let it happen, but i don't want most of my metalflake and such to settle on the bottom (effectively one side) of my tube-in mold or at the top or bottom of the verticals.
====

Many thanks in advance,

Steve Milone
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I have used a coffee/candle warmer for my small up to 6 oz pours to help with bubbles and move things along. 5 drops per oz should be ok but it depends on what your "proprietary test additive" is I use 6. I keep checking until it starts to turn to fake maple syrup you tell when there is change in how it streams off the stir stick.

At that point pour.
 
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Warm the resin in the cup with a light bulb over it. I use a metal clamp light. Once the resin is warm and thin (stirs easily) then add the catalyst. I only use 3 to 4 drops per ounce. Also, warm your mold and pressure tank with lights if possible. If your pouring colored blanks you can leave the resin under the light bulb if the shop is cold, to help it thicken up. Occasionally stir it to check consistency. Once it starts to gel, pour and swirl. Its one of those things you will get the feel for as you do it over and over. Of course if your clear casting or needing your resin to penetrate an object in the mold, pour while its still in a thin state. I let my PR Silmar 41 set over night. (18 + hours) to cure. Get them too hot or try to cure them too quickly with catalyst or heat and they get brittle. Good luck!
 
PSNCO said:
Get a new bottle of MEKP. I've had 6-9 month old PR work just fiine, but found the MEKP was worthless after about 3 months.
Click to expand...

This right here. I've used 6-8 month old resin without any problem, but old MEKP can be a real issue. I've even had old MEKP discolor new resin when I was making a clear cast. Swapped it out for a fresh bottle and ended up with a perfectly clear blank.
 
To all who posted, thanks very much. Sounds like it is a combination of older catalyst and inexperience jumping the gun. Funny tonight my son wanted to cast something anything, so he grabbed a dry leaf out of the yard. 2 Oz in a paper cup with 8 drops of the range make, waited about 10, it was not quite honey and put the leaf in, right before it gelled. Weather is same, I wonder about the pearl ex, metalflake etc how much they affect it.

I mixed this up and poured six 3-component verticals and a couple tube in tonight, anxious to see how they work out. Not anxious enough to crack open the pressure pot though.

I will look for some mekp locally I hate paying more for shipping than product LOL meanwhile I will take each pour as an adventure

Thanks again
 
It's ok to have mistakes, they're learning experiences. It took a few gallons until I started getting consistent results with different effects I wanted. There's a bit of a learning curve where you develop a feel for it. For blanks that don't turn out as desired, turn them for practice. I still have several blanks that either didn't turn out good or are several different layers that I poured from the leftover resin. I make "ugly brush handles" for shaving brushes and give them away at B&B without a knot. Some of the guys really like what they get - beauty is in the eye of the beholder - and it beats throwing the blanks out. Don't expect everything to go as planned in the beginning, but you'll get it.

And yes, mica does affect the curing. It seems to me black will always set faster than any other color, but the only way to get a feel for the colors/media is through experience. Ambient temperature, humidity, and even the alignment of Jupiter in relation to the moon's orbit on the third thursday of each month all seem to have an affect as well. :wink:
 
Thanks Cliff, I will check Michael's in my travels this week.
Jay, I'm all aboard a far as "happy little accidents". Just put the OP out there in case I was fighting a losing battle with old product. Now that it seems the catalyst is iffy, I get to go all Bill Nye in the shop until I get some new MEKP.

That part annoys my son (16) because it isn't predictable etc, but he is coming out of that shell. We have mutt blanks all over from cutoffs etc, now we add to that PR and Alumilite cutoffs and try again's.

Copious notes on weather temp etc, open date of resin (and now mekp) type/size of mold, preheat temp and time, Pearl-Ex or whatever other add in, color etc, how much catalyst, time to thicken... That could get out of control, but I will nail it down as time goes on.

Thanks for the encouragement!
 
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