resin casting

John, I will swap your ceiling for my shed interior walls.....Mike

Ha .Marty Your on .

John

Just another word of thanks for all the help and info....cheers for the extra photos Mike...will definitely try out a few wheels using that method.....thought I would post a couple of extra pics to show the results....not much though a good start from my point of view and I can see this being a very useful skill to develop...firstly the item shown on the first cast which was the mounting bracket for the gun shields on the flak37 which is absent on the trumpeter kit....

Too complicated to scratch so more than worth the effort...if only I could get the other one to come out as well...three attempts so far ....and then the little ammo box shown earlier to which I just added side handles from plastic strip and a drop of paint....

Not all plain sailing...did mix up a batch of rubber which didn't cure overnight and was impossible to remove from the master...I know...I tried!!!....but following earlier advice I let it sit for another day and although it didn't set fully I was able to peel it away from the master copy so was able to save it for another day

Cheers again to all who contributed tips and info ...happy casting...Marty

Hi Marty

As you say it is a useful skill even if, like me, you stick to simple things. The ammo box looks great and having the mould you can make as many as you need.

Jim

Marty

There has been a whole lot of great advice posted so far, and as you and Jim say this is a good skill to have.

The postings, so far relate to using moulds made of RTV (room temperature vulcanising) rubber which I do use. I do however also use another product to make moulds; latex:

I have found this latex easier to obtain than RTV, a couple of art/craft shops sell it locally where as nobody locally sells RTV.

Using it is a very different technique, and not really suitable for highly detailed or small parts. I bought a sandbag trench wall which I wanted to mould it using this latex:

I glued the master to a piece of plywood and then applied the latex rubber. The first few layers were applied using a small paintbrush, and dried using a hairdryer, after a few layers I added some of the thickening agent and added a thicker layer, again drying it with a hairdryer. An alternative method is to dip the master into the latex to apply a thin layer.

It takes a lot longer using this latex, probably a couple of hours to build up a thickness of bout 3-4mm, and 24 hours to dry completely.

One problem with it is that it is flexible and will be distorted by the weight of the resin. My 'Heath Robinson' solution is to fit it into a box:

A roughly fitting wooden 'box' is made and pollyfiller added to make a close fit with the mould. Only when this is dry did I remove the master from the latex for the first time.

It is ready to pour the resin, or plaster depending on what you are making.

Finally, when mix resin I always have a little left over, so I keep near me a couple of moulds like these to hand to take the excess:

The top one is a home made RTV mould of a pedistal base for busts, the lower is a commercially available mould for blocks, which I have built up a supply of. Other moulds I use are wooden barrels or ammo crates, small things which will always be useful.

Finally, when I cast something large like the sandbags I often pad out the new resin by adding into it odd bits of resin, like the bricks, or the resin casting block off other models. Saves waste.

Peter