Need info on cast molding please.

[Reaver]

Hey all hope you're all well. I'm trying SMOOTH-ON a two part Silicon rubber for the first time. Everything went well and I thought I had enough but as it turns out I was a bit short. I was not able to complete the mold and have about an inch or so undone. Can I add more at a later time, say when I get the new shipment or do I have to nix it and start over? Any help would be greatly appreciated.

Thanks,
Reaver. ...

 

[itsgreg]

You should be fine to add more. Never used smooth-on brand(assuming it's just condensing RTV silicone) but as long as you top it up with the same type of silicone it'll be seamless.

 

[Reaver]

You should be fine to add more. Never used smooth-on brand(assuming it's just condensing RTV silicone) but as long as you top it up with the same type of silicone it'll be seamless.

Thank you so much. The only reason I tried smooth-on is because it was on sale for like $30. Since I know what to do and not do I can move on to the good stuff.
After all this time, this it still the coolest place to learn and share.
Thanks.... .

 

[itsgreg]

Thank you so much. The only reason I tried smooth-on is because it was on sale for like $30. Since I know what to do and not do I can move on to the good stuff.
After all this time, this it still the coolest place to learn and share.
Thanks.... .

Nothing wrong with Smooth-on, I just don't use it cause I'm cheap! lol.
I buy whatever condensing silicone I can get cheapest, that's got the pot life & shore strength I need.

 

[clonesix]

Silicone RTV Always sticks to silicone RTV. You're good to go with back up when it arrives.

 

[TheTrekNerd]

If you used mold release, there could be problems, and I've had layers delaminate before even without it. If there's only an inch to go, you might as well try.