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Molding a gasket no longer available

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Gliderman8

Gliderman8

Great Pumpkin
Gold
Online
So I need a gasket for our kitchen pull-out faucet. No parts available from the Italian manufacturer. The original was cracked on the top. See pics. I decided to make a mold of the part and try to make one out of silicone.
Will try molding one once the mold dries completely. Fingers crossed!

Original broken gasket
image.jpg

Mold I cast for the new one
image.jpg
image.jpg
 
I was going to guess you're scr*wed... but I like your attempt. :) I'll be very interested if you can pull this off.
 
I assume you mean 2-part silicone. RTV would not work cure well and is very thick.

I have made prototype parts in previous jobs using 2-part silicone rubber. My suggestions for you are limited as success will probably come from trial and error more than anything I will say.
Use a good mold release on the cavity.
If you have a source of vacuum and some form of bell jar (or can improvise one) use that to draw all the air out of the silicone as it is curing. The finished part will be smoother without any trapped bubbles.
When selecting your silicone, make sure you find one that is relatively close in Durometer (hardness) to what you are replacing. For a comparison, a typical Buna o-ring has a hardness of 70 Shore A.
 
Thanks Doug. I am aware of removing the bubbles through the use of a vacuum. Can RTV be thinned?
 
I don't think RTV can be thinned. The other problem is that RTV cures best when exposed to air. The thick sections inside a mold will remain uncured much like the center of a tube of caulk remains soft even after a long time (like years of sitting on a shelf).

If you don't already have a source for 2-part silicone, take a look at MicroMark
https://www.micromark.com/
They are a hobby supply company. From their homepage search for "silicone" and you will find lots of mold making and casting supplies.
 
Thanks Doug.
 
I've used Devcon products with good result. Made a mold for the diaphragms in the BMC heater valves back when the valves were "unobtanium" with success. Used their metal filled epoxy to repair the bronze water pump in a 1906 Ford Model S, too.
 
DrEntropy said:
I've used Devcon products with good result. Made a mold for the diaphragms in the BMC heater valves back when the valves were "unobtanium" with success. Used their metal filled epoxy to repair the bronze water pump in a 1906 Ford Model S, too.
Click to expand...

I used their product also when I restored my steering wheel and it's holding up very well. :encouragement: PJ
 
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