Thread: Pen Blank Moulds

Making a mold is probably about the same price as buying two. Most of this
post is about using RTV to pour a mold, but people have also done it with
silicone caulking.

One easy way to get started is to put aside some blanks that have no voids or
cracks and use these as your 'masters'. I like TruStone blanks for masters, because
they don't float when you pour the mold. Now I tape them down anyway, but they
still give a nice surface. It helps to 'break' the sharp corners with a bit of sandpaper..
but remember that you'll be working upside down. The rounded corners will face up
when you pour.

Pick up a gallon of RTV silicone and a roll of double stick tape.

Make yourself a mold box out of wood, corian, a plastic cutting board.. doesn't matter,
but give it a smooth finish and put a coat of paste wax on it. If you screw the box
together you can dis-assemble it and re-use it.

Make sure you measure carefully when you make your mold box, as the mold won't
do you any good if it is 1/4" too large to fit in the pressure pot. DAMHIKT

For single blanks, you can get away with 1/4" walls around and in between blanks.
For a 'slab' mold, you want at least 1/2" thick walls. Otherwise the weight of the resin
will push out the walls when you pour.

On a smooth, flat surface (I use a sheet of leftover corian) tape down your box frame
with double stick tape. I also run beads of caulking in the corners, but it isn't really
necessary. But don't use silicone caulking for this, the RTV will bond to it. Acrylic
caulking is fine. This will stop the RTV from leaking out of your box. You could also
use a hot glue gun for this, but you can't smooth it out as well without burning your
fingers.

Position your masters in the mold box and hold them down with the double stick tape.

Pour and wait. De-mold after 24 hours. Typically, it needs another couple of days
to cure more fully. I put it in a warm toaster oven (150 degrees) for a few hours, but
after that I just leave it for a few days. I also dust the surfaces with baby powder.

Enjoy

A couple of tips:

1) Make sure you LEVEL your work surface before you pour your mold . If not, you'll
either pour crooked blanks, or forever after you'll have to 'un-level' your pressure pot
every time you pour

2) Even though a mold release isn't strictly necessary with silicone, it will significantly
extend the mold life.

3) A hair dryer will help eliminate air bubbles in the silicone while it sets.

4) The baby powder helps with surface tension when you pour. It will be on the surface
of your casting, but it will be turned away. It reduces bubbles in the casting.

I bought 2 silicone moulds (or should I say molds) from Gadget in the US and had them shipped together with quite a bit of other stuff by a friend in the US.

"http://www.penturners.org/forum/showthread.php?t=39649&highlight=gadget+mold"


They are great, but I have also made some moulds by cutting up some white cutting boards from the cheap shop and screwing them together, both several single moulds bigger than normal for casting "worthless wood" and several that allow me to cast a block of PR, not dissimilar to what grub32 uses from memory.

One of those cutting boards is only about $6 to 7 dollars and it is a cheap and easy way to start.

From memory the silicone moulds from Gadget cost me about $25 each, and that was when the $A was actually worth something

Buying the silicone resin is also not a cheap exercise, each of these moulds weigh about 700gr, so work out how much that will cost you from Barnes and the like.

You certainly need the 1/2" walls on the multiple moulds.

I use white melamine board.Cut to size required, super glue together,hot glue to joins to seal. PR will not stick to it and throw away after each pour. It is cheap and works.

The least expensive is pvc and there is much less waste of the PR since you aren't cutting/turning off the corners. It takes less time to turn when it is already round too.

Do you put a release agent on the pvc.

Terry

I use electrical conduit and no release agent is needed. I drilled a hole in some timber to use a s a stand but you can also buy the plugs from the electrical wholesaler.
Lets know if you want a photo. You could use plumbers pipe but E conduit is the right size and at $60 a stick you can even get clear

I don't use any release agents and they slide right out in under an hour.

Originally Posted by Simomatra

Terry

I use electrical conduit and no release agent is needed. I drilled a hole in some timber to use a s a stand but you can also buy the plugs from the electrical wholesaler.
Lets know if you want a photo. You could use plumbers pipe but E conduit is the right size and at $60 a stick you can even get clear

plugs?