Post by captaincook on Oct 1, 2022 16:23:05 GMT -5
Newbie question: I mis-calculated the amount of Plat 25 I needed for a mold and realized it when the template was only half-filled. I've kept the form covered so it is dust-free and the silicone in great shape, soft, smooth, and not sticky. My question is if I pour a new batch of Plat 25 on top to finish filling the form, will the new adhere well enough to the old that it won't leak when I pour epoxy into the mold, and will stand up to the stretching necessary to de-mold both the template and parts I cast? I want to use this mold to cast several parts and it has about a 10 degree outward taper so it has to be durable enough to stretch as the part is pulled up through that taper. Thank you for any help!
Ive poured new silicone rubber onto old, and it separated. That was because of dust build up. A cover should help. I now just clean the surface of the old by scraping the dust off with a exacto blade and it adheres to the old just fine. Hope that helps.
Yes absolutely it will stick just fine - I've had spots on a finished mold where I had to cut some out (dust got in it after the pour) and just poured new right in the hole with no separating or anything. But you DO need to be sure to clean it first if there's a chance dust got on it. A quick wash with a little water and a drop of Dawn is all you need then make sure to let it air dry or use a paper towel.