silicone mold help

[epochcraig]

hi there all i am after some information i am building my first own helmet and i have made the model out of fibreglass covered in filler all sanded down ready and primered i am using silicone to cast the mould do i need to coat the model in a releasing agent such as petroleum jelly or can i just apply the silicone direct to the model thank you

 

[bunker1]

You could apply the silicone directly onto the piece, but you do risk the primer being pulled off in places due to the suction formed between the helmet and the silicone.

I would always err on the side of caution by creating a barrier between the two surfaces.

A spray release wax is always good. If this isn't available, then I generally use regular floor wax watered down with white spirit to a thin consistency. Brush on a thin layer and let it dry. You're good to go.

Hope this helps.

 

[Eaglewood]

use a general spray release agent if possible. Unless the primer is non compatable with the silicone- it should release ok-

 

[PepMaster]

I've heard that PAM works great as a release spray, after all PAM helps you pull it off.

 

[epochcraig]

brilliant thank you for the help ...what is PAM ? so petroleum jelly isnt good then thank you

 

[epochcraig]

i would show you a pic but dont know how to put it on here lol

 

[SonOfPumpkinhead]

Don't release it at all... at MOST hit the model with a thin spray of crystal clear from kryalon just to seal the bondo but a general rule is that silicone won't stick to anything but silicone. You don't need a release on the model just seal the bondo. Also, make sure your using a tin cure silicone, not a platinum.

 

[epochcraig]

thank you all for your help will give it a shot today and upload photo for you to have a look thank you

 

[Elvis]

good info here thanks!