Help: resin leak from silicone mold

[Spidey83]

So I recently made my first silicone cast and have had leaking of resin from the mold. I ensured it was tight but still have a leak. Does anyone know an easy fix for this. Now the mold is about 40 lbs and is a two part mold. Just curious if there is an easy way to seal where it is leaking from to keep it from leaking out continuously. Thanks

 

[auzorann]

Do you have any pictures of the mold?

 

[CPTRogers]

Bump. I'm having the same issue. All of a sudden my molds are leaking.

 

[cavx]

Generally, you are supposed to clamp the two halves together and apparently that seals the molds. However, after losing so much resin to leaky molds, I designed mine to act like a bowl and plug.

Given you guys have already invested money into making molds, the last thing you want or need to read is to make a new mold, so is it possible to modify your existing molds by building up a wall around the join?

 

[CPTRogers]

I cleaned my molds today. I scrubbed them with a toothbrush and acetone/alcohol. Seems to have done the trick. Maybe a super thin layer of resin cured and created a seam.

 

[sjanish]

Hot glue.

I don't know if this will work for you molds, it will depend on the way you designed them.

On these molds I only needed a part of the master and did not want to mold the whole thing or cut up the master.

This is the bottom of the mold. I wrap packing tape around the sides of the mold and stick it to itself. Then I plug the hole with hot glue. While the glue is still hot stick packing tape over it and secure it to the tape on the sides. It works great, but I have to redo the plug for every casting.

This one is similar, but I turned the hole into the pour hole. This one is a bit tricky to get a good seal, but it works.

 

[cavx]

I think these guys are all doing 2 part molds to capture the front and the back.

 

[CPTRogers]

Yea 2 part

 

[BrundelFly]

You need more space around your part. Your Part is WAY too close to the edge.
Hopefully, you are not planning on casting very many. You could try making a quick plaster jacket around your existing mold, if you can get the master back in it, or try it with a casting.
There is a reason we use fiberglass or plaster as a mother jacket for large molds. Also saves on Silicone.
Good Luck!

 

[sjanish]

I think these guys are all doing 2 part molds to capture the front and the back.

Both of the molds pictured in my post are two part molds, but, they were designed with this in mind.

 

[cavx]

There is a reason we use fiberglass or plaster as a mother jacket for large molds. Also saves on Silicone.
Good Luck!

So does the fiberglass stick to the silicone or do you make keys for alignment? I want to learn how to do these types of molds.

 

[Darksyde13]

Here are a few techniques from BITY. They show several techniques but in the end the process is very similar wether you use fiberglass, plaster, plaster bandages, or resin.

http://www.brickintheyard.com/videos/playlist02.php

 

[Snow Builder]

I run vaseline around the edges of both sides of the mold -helps to seal the small gaps and I don't (usually) have a problem with leaks.

Hope this helps.