Making your own molds- where to get the silicone?

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BigguyZ

BigguyZ

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OK, so I took a stab at making my own silicone mold, ala the library article. However, the silicone I used obviously wasn't acid cure like the artivel suggested, as it's been about a week and it's still not cured! :eek: So, where do you get the proper caulk to use? I went to Menards, and couldn't find anything noted as acid sure silicone caulk. Is there a specific brand/ type that people use?

Thanks!
Travis
 
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I've used GE silicone. You can tell if it's the right one because it says
100% silicone .. watch out for the ones that say "Siliconized" .. that's not
the right stuff. It's usually marked for Kitchen and Bath. The big box stores
almost always have it..
 
NewLondon88 said:
I've used GE silicone. You can tell if it's the right one because it says
100% silicone .. watch out for the ones that say "Siliconized" .. that's not
the right stuff. It's usually marked for Kitchen and Bath. The big box stores
almost always have it..
Click to expand...

I used 100% silicone, but the article gave me the impression that there's two types- Acid cure and air cure. The acid cure's supposed to cure in the center areas quicker, whereas the air cure will develop a skin, and the center will take a lot longer to cure.

I'll look for the GE silicone today, and see what I find.

Thanks!
 
Check the auto parts stores. look for RTV sealant. I picked up this brand, but don't remember if it was this exact product. There were several different colors, hi-temp and regular, etc. but you just need an RTV I believe, so don't worry about all that other stuff, just get what's cheapest. Maybe get the hi-temp if you'll be post curing in the toaster...
http://www.permatex.com/products/Au...matex_Hi-Temp_RTV_Silicone_Gasket_Sealant.htm
 
I suggest PVC pipe. OR you could give me your address and i could mail you this slab of a hunk of pen blank mold that i have. It only weighs about 20 pounds lol.

I switched to lengths of schedule 40 PVC pipe. I use blue painters tape to seal the bottom, and rubber bands to hold several together at once. You can fit a bunch of em in your pressure pot, and you can get 1/2" pvc for slims and Euros, and 3/4" pvc for all the rest. You can even cut shorter mold sizes for single barrel kits, or extra long molds for closed end pens.

I prefer the PVC cause it is cheap(For less than the cost of silicone, you can buy enough PVC to make about 50 molds), easy to work with(Pour, pressure, bake, let cool, knock out with a large punch or turn a tamp!!), and the blanks look better i think. When you pour them on a flat surface, like in a silicone mold, you get the weird shiny spots on the top and bottom of the blank. When you pour vertically, you eliminate these two spots. The striations also look better in a verticle blank. Of course this is just my opinion, but it is what works for me!
 
Hey Travis, I used the regular tubes of "caulk" type silicone sealeant. I found that as you make the mold, fill it up about half way and let that cure. Then, come back a day later and fill in the gaps and top off. This allowed my mold to cure much faster (after a failure the week before). Think about it. In a sealed container such as the caulk tube, the silicone will stay uncured for a long time. When you lay down a layer of silicone app. 1-2 inches thick, as it cures from the outside in, you eventually reach a point where the inner silicone is effectively sealed off from the outside, hence it will sit there and never cure. That is why 2 thinner layers will cure better than one thick layer.

BTW, I appreciate the trade for Fountains to Rollerballs. I am looking forward to hearing from you when the blanks are done.

DJ
 
Also, with PVC, the blanks are already round, whick is especially handy for drilling on the lathe. And the outside surface is near flawless, so you have a decent idea of what is inside right off the bat. My silicone mold produces good, useable blanks, but the edges are rough and ugly. Of course all of that gets turned away, It does make it difficult sometimes to judge what is inside though.

Hope all this helps.
 
CharlestonPenWorks said:
Hey Travis, I used the regular tubes of "caulk" type silicone sealeant. I found that as you make the mold, fill it up about half way and let that cure. Then, come back a day later and fill in the gaps and top off. This allowed my mold to cure much faster (after a failure the week before). Think about it. In a sealed container such as the caulk tube, the silicone will stay uncured for a long time. When you lay down a layer of silicone app. 1-2 inches thick, as it cures from the outside in, you eventually reach a point where the inner silicone is effectively sealed off from the outside, hence it will sit there and never cure. That is why 2 thinner layers will cure better than one thick layer.

DJ
Click to expand...

That is an excellent tip!! When I made my first couple of molds it took nearly a week to fully cure. I just used clear silicone that you normally use on the exterior of windows.

Now I use OOMOO products. http://www.smooth-on.com

A bit more pricey but it works really nice!!
 
PTownSubbie said:
That is an excellent tip!! When I made my first couple of molds it took nearly a week to fully cure. I just used clear silicone that you normally use on the exterior of windows.

Now I use OOMOO products. http://www.smooth-on.com

A bit more pricey but it works really nice!!
Click to expand...

The OoMoo is very, very good. The Mold Max 40 from Smooth-on is very nice as well. The MM40 is firmer, and has a longer library life. Cost is about the same. Mold Max comes in different durometers so you can have very flexible molds, to very rigid molds. You have to use a scale to dispence it as it is not a 1:1 silicone like the OoMoo products.

However this is not the same as brushing on bathroom, tube type caulk, and hoping that it cures fully or you didn't get some extra voids...
 
Well, I'm just looking for something cheap and quick that I don't have to do a special order for. I'll look into actual casting silicone down the line.

As far as pipes go- I definitely think that'd be a great way to go if I was looking for just a solid blank. However, I'm looking to do some worthless wood casts and similar, so the tubes may not be the best for that.

I'll try DJ's suggestion of building up the layers over time. That sounds like the most feasible at the moment.
 
you can go as thick as half an inch with the hardware store stuff and it will still cure in the time the tube says it will. usually 24 hours or so.
 
there are also lots of pre made plastic containers that will work. So far, all of them with the "5" inside the recycle symbol on the bottom have worked for me. Lots of containers with the 5.
 
BigguyZ said:
Well, I'm just looking for something cheap and quick that I don't have to do a special order for. I'll look into actual casting silicone down the line.
Click to expand...

If you look on the smooth-on site, you may have a distributor in your area where you can pickup a trial sized package. I buy mine locally. Just picked up another package a couple hours ago.

I use the OOMOO 30 brand. This stuff in plyable and is durable as ever.
 
Take the 100% silicone and squirt it into a plastic bowl with soapy water kneed it in your hand for a few minutes befor putting it in the mold form. The water speeds up the cure.
Mark
 
The Wood Duck said:
Where do you get the material for your pen blanks, to pour into the PVC mold?
Click to expand...

It all depends. If you just want to grab some locally to try out casting, you can pick up small amounts at Michael's craft store. (Castin' Craft brand acrylic resin) But it's more expensive than buying in bulk. You can buy cheaper online from several different places. Alot of people use Alumilite also which is a slightly different resin...
 
For silicone molds, I use GI-1000 by Silicones Inc. Very user friendly, no pressure pot needed since it is a self degassing silicone. 10:1 ratio. 10 activator to 1 part base. TAP Plastics has something similar just called an RTV silicone. I use GI-1000 more for SPFX stuff.
But it can also take up to 500 degrees for baking aswell. Cure time, generally is about 18-24 hrs. But it can be pushed to cure in 4-5 if needed. You'll just go through activator more quickly.

Smooth-On has some great products too they too have a RTV very similar to GI-1000.

As for casting my own blanks, I have not tried yet. My question is, when mixing the pigments / colorants, do you add to the resin first before catalyst or after? I imagine it would be before otherwise I would think the catalyst would create separation and not allow to mix well.
 
I tried the caulking silicone once, then bought the Smooth-On silicone mold making material. I have better things to do than waste my time with the caulking silicone, did it right the second time with Smooth-On and have never looked back.
 
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