Problem with Casting

[Rounder]

I have a question for you more experienced guys on a problem I seem to be having with my casting. I am using the Casting Craft resin from Micheal's. I poured a mold last night in one of the soda bottle molds. Within an hour or two, a crack had already shown up in the casting. You could see it through the clear plastic of the mold. I have poured 5 of them in these molds so far and this cracking has occurred on 3 of them. I had a little under 2 ozs. of resin and added 8 drops of catalyst. Any ideas as to what might be causing this?

 

[seamus7227]

i would say your resin got too hot! try using less catalyst

 

[ZanderPommo]

wats your local temp? for me thats just the right amount but if you're in 100 degree temps or somethin that could overheat it

 

[PTownSubbie]

i would say your resin got too hot! try using less catalyst

+1 on this. Likely heat related crack..... I have had it happen before also...

Did you feel any excess heat when you checked it and saw the crack?

 

[Rounder]

i would say your resin got too hot! try using less catalyst

+1 on this. Likely heat related crack..... I have had it happen before also...

Did you feel any excess heat when you checked it and saw the crack?

Local temps last night were in the 30's. 66 During the day. I did this in a well vented room in my house and it was 71 degrees. When checking it I did not feel any excess heat. Just very slightly warm. I will try to get a picture tonight after I get home before I remove it from the mold.

Thanks for the ideas.

 

[EBorraga]

How much MEKP did you use per ounce of resin?

 

[sbell111]

How much MEKP did you use per ounce of resin?

Per the OP, he used a little more than 4 drops per ounce.

 

[EBorraga]

Somehow I missed that part Steve:biggrin:. I must've been exposed to way to much PR fumes!!

 

[its_virgil]

Heat from curing can definitely cause cracking. Using round molds can also compound the problem. Heat is dissipated out the exposed surface on the casting. With round molds the only exposed surface is the open end. Heat builds up faster than it dissipates so it collects in the interior of the casting. Too much heat buildup and cracking can occurr. I would reduce the MEKp and see if the casting gets better. I use 3 drops per ounce with horizontal molds. You may want to try two and see what happens. Good luck with solving your problem and happy casting.
Do a good turn daily!
Don

 

[DurocShark]

Castin Craft is also pretty inconsistent in its formulation. A big reason for buying Silmar 41, which so far has been very consistent.

 

[Rounder]

Castin Craft is also pretty inconsistent in its formulation. A big reason for buying Silmar 41, which so far has been very consistent.

I have thought about using the Silmar but just can't seem to find any 40% off coupons for it anywhere, lol.
Thanks again for all the suggestions. I will try the cutting back on the catalyst and see how that works.

 

[sumterdad]

As far as the silmar goes you are right you can't find discount coupons for it but if you calculate the cost of the casting craft per quart it is around 21 dollars. Then gas to go get it and then you have to buy the memo for it. That comes to between 75 to 95 dollars. Not including Your gas. I just ordered a gallon of silmar from illstreet and pd alittle over 50 dollars for it. Plus it comes with the mekp. So I will be buying it from illstreet more often. Just my two cents. Maybe the more experience guys will have something different to say

 

[navycop]

Is this the right stuff? http://www.carbon-fiber.us/shopping_cart.php

 

[DurocShark]

Is this the right stuff? http://www.carbon-fiber.us/shopping_cart.php

This: http://www.carbon-fiber.us/silmar-clear-polyester-casting-resin-gallon-p-416.html