Silicone mold storage?

[Kit Basher]

I just made my first silicone mold. Do you folks have any suggestions for storing these for future use?

[Ace-Garageguy]

60-80deg. F, low humidity, covered (prevents dust accumulation) and out of direct sunlight (most mold materials have no UV inhibitors). Also not near a heater vent.

[Casey]

Another option is to cast as many parts from the mold as you can until it wears out. That way, you have plenty of parts on hand and don't need to worry and storing and preserving the mold.

[Mike Kucaba]

Store at least one part in the mold and all the other advice. I like Casey's the best. You could also make molds with a addition cure RTV which has a greater shelf life as opposed to condensation cure.

[Kit Basher]

Thanks for the replies, guys. Let me see if I have the idea: put some parts in it, put in a sandwich bag, and store it in a dark cabinet in my house. I don't know if it is "addition" or "condensation" cure. I used Smooth-On OOMOO-30.

[MAGNUM4342]

Covered, as in "in a box" yes. In a plastic bag? NO. The plastic bag will only serve to leech essential oils out of the mold and degrade it faster.

[Kit Basher]

Thanks, Kevin, you saved me from another mistake. It sounds like these things will degrade over time no matter how they are stored. Is that right? If so, how long do they last?

[Mike Kucaba]

Thanks for the replies, guys. Let me see if I have the idea: put some parts in it, put in a sandwich bag, and store it in a dark cabinet in my house. I don't know if it is "addition" or "condensation" cure. I used Smooth-On OOMOO-30.

Addition cure RTV is sometimes referred to as "platinum" cure, and condensation cure is referred to as "tin" cure.

Somewhere in Smooth-on's literature is one of those words. HTH

[Ace-Garageguy]

Smooth-on technical lnfo for Platinum Cure silicones:

http://www.smooth-on.com/Silicone-Rubber-an/c2_1115/index.html

For Tin Cure:

http://www.smooth-on.com/Silicone-Rubber-an/c2_1113/index.html

[MAGNUM4342]

Hugh, there are a few factors in how these things break down but yes, silicone molds will start to break down from the moment they cure. Length of time they last will depend not only on storage but shore hardness, brand used and of course how much they are used. Since the chemical reaction of the resin causes heat each use will break them down further. If you warm your molds (essential only when using clear resins) they will break down faster. The higher the shore hardness the slower the oils will leach. Environment plays a factor as well. Dry climates are harsh on them but a more temperate climate will degrade them slower. If you live in Nevada or Arizona they will break down quicker than if you live in say, Iowa or Ohio.

Storing them with a casting in them is something I have not tried yet but it seems to me that if you do that, as the mold ages and loses those oils and shrinks, a casting left in the mold will only cause cracks. You can get some mold conditioner that will help. It's king of like WD40 for silicone. It will help the mold last longer if used regularly every few castings and right before storage. You can also use vaseline petroleum jelly. Coat the entire inside of the mold with vaseline right before storing them. Store them in a non-plastic box away from direct light or heat. The storage area should be cool but not cold. As Bill said between 60 and 75 or 80 degrees is best. No matter what you do, the tin cure molds will be useless in less than a year and platinum silicone will last between a year and two.

Most of this I had to learn the hard way.

[Kit Basher]

Thanks Kevin and Bill. Since this seems to be a "use it or lose it" proposition, I guess I will follow Casey's advice and cast until it's worn out. Thanks again.

[MAGNUM4342]

That's actually the way to go if you aren't a regular caster. And heck, if you wind up with a bunch of extra parts you can use the extras to trade with folks for other parts here.

[Steven Zimmerman]

Also, keep / store the master, so that you can pour another mold when one goes south. I have drawers full of masters, already affixed to their boxes , ready to pour. I know that some of your major casters just spray the mold with release, and the molds last a long, long time.