Mold storage

[Lamenter40K]

What is the preferred method for storing your silicon molds? Right now I've put it into a ziplock bag but I'm not sure if that's right.

Also the Alumilite directions said that after so much use you should bake the mold at like 400 for a couple hours to push the resin out? It also mentions rubbing one of their compounds (maybe it's called 200 or something like that) onto the mold during storage and what not.

Are there any issues with writing on the silicon with a sharpie for quick reference later? I wasn't sure if the silicon might react with the ink and cause some weird issues.

Thanks guys!

[paulson games]

I've written on a few of mine witha sharpie, the only issue is the marker doesn't stick for long

No adverse effects on the silicon.

[mangozac]

I just stick mine in a box and seal it up. My production moulds don't tend to last that long anyway (lifespan of a couple of months max) simply due to wearing out with use. The baking thing has been discussed before and I'm pretty sure I talked to my supplier about it, who told me not to bother. That was from the perspective of maximising production lifespan, not shelf lifespan though.

Nothing sticks to silicone! Stick the moulds in a ziplock bag with a labelling strip (the opaque part of the bag) and write the name on there. But no, the ink won't hurt the silicone.

[Lamenter40K]

Sounds good, thanks for that one.

So when people talk about mold "life" and/or library or shelf life, what's the difference and are these referring to age, use or a combination of both?

To clarify if I use a mold a few times, throw it in a ziplock and leave it alone for a year will it still be good? Whats the average amount you can use a mold and what happens when they "go bad"? Do they start drying out and cracking?

[mangozac]

Mould life is generally how many "pulls" you get in production. Library shelf life is just that: how long the mould will last sitting on the shelf. Both depend heavily on the brand of silicone, but there are techniques (like the baking one) that can be used to extend them.

When the mould wears out the silicone generally gets hard and brittle, so it tears easier and becomes no good for casting.

I would expect to get at least a year of shelf life, but again it depends on the product. I'm pretty sure Blind Pig has a library of moulds made from Pinkysil that are a few years old and still good.

[Lamenter40K]

Ok, thanks for the answer. How many pulls does an average mold have in it or does it depend entirely on the type of silicone?

(I am a questioning person by nature and I know it can get old for some people so I apologize for all these ultra basic questions).

[mangozac]

Again it depends heavily on the silicone, but also on the model - a model with lots of tight, square detail is going to put a lot more stress on the mould. I estimate that at the moment I'm getting around 40 pulls per mould. The Ultrasil I was using previously would give me around 25-30 pulls of the same part.

Don't forget to try the search function, or even google with the condition "site:http://www.resinaddict.com/", as you will probably find that some of your questions have been discussed before

[Lamenter40K]

Thanks, I'll do some digging before my next round of silly questions. I appreciate the info.

[Lane]

[Lamenter40K]

Lane thanks for that. I'll have to make sure to pick up silicone oil with my next order.

[blind pig]

I find that Ultrasil moulds (depending on the detail being cast) will last for about 30 pulls before they degrade to a point where the product is no good and requires more time to clean up than is worth it.

Pinkysil will give about double that number.

As for shelf life or library life, ultrasil gets old after about three years, my Pinkysil moulds can still be used after not being touched for over six years.

The best silicone that I have ever used for shelf-life is the old Dow Corning RTV that was the only stuff available befor Barnes came along. Some of those DC RTV moulds that I have are over 15 years old and still used once a year without seeming to have degraded!

I store my moulds in ziplock sandwich bags with what is inside written on the outside and put a little talc in there before sealing. They are then stored flat, in the dark on shelves in my spare bedroom.

I have put clean, old degraded moulds in a foodprocessor to make a fine powder as a filler for my larger (5+ Kg) moulds for making weapons, without any noticable ill effects.

[mangozac]

[Lamenter40K]

Wow, interesting stuff. From what little I know I've heard of fillers in resin. Is filler in silicone something people do as well?

[Lane]

Recycling old molds is not actually using a filler. In fact grinding up the old mold is not required. I several cases I made perfectly functional molds by placing chunks of old molds in the corners and other dead space of a new mold. Since the silicone sticks to itself the molds come out just like using all new RTV.

[blind pig]