Making castings is an incredible experience and seeing your first one "pop out" of the mould is very exciting, no matter what quality it is.

As with any new techinque, there is alotta of experimenting with some disastrous results and wastage.....but also some pleasing outcomes.  While the initial cost of the RTV is around $50 and a little extra for the casting plaster, I knew my perseverance would pay off financially, as I like to soak up my projects with lots of detail.  

Discussion about using original castings to make copies has been discussed at length by many modelers, but I am still lead to believe, making copies for personal use is not illegal, in fact many articles have been published by Manufacturer's on how they produce castings and moulds. They know for every 100 people that read or see a clinic about Mould making, only a handful might ever have a go.....That's why most are still in business.......... It is the guys who sell crap copies for profit, that get up my nose......

 As mentioned earlier, not long ago I knew nothing above this subject, but as I normally do, asked alotta questions, made alotta mistakes and now can produce fine detail items. A day trip to Solid Solutions, who are suppliers of the raw materials, was worth the effort.  After a few hours, with them, discussing the various products that were available, I decided on just a few.

Solid Solutions.     www.solidsolutions.com.au

RTV585   -   this makes the moulds.   

Available in 1kg ( $57.25) and 5 kg  ( $211.50 ) container.   

Do yourself a favour and purchase 5kg.   Cheaper.  You can go halves with your mates.

Mix Formula.  100 ml RTV585     ADD     5mm catalyst.

I make a maximum batch of 200 ml at a time. Just gets a bit tiring on the hand when mixing.

When the mixture is right.?????  When you get tired of mixing. Never failed yet.

Use Plastic mixing containers. When RTV dries, it can be easily pulled out.

DO not use glass mixing bowls. RTV sticks like glue to the sides. Have a can of coke handy. It’s thirsty work.

Make up a lot mould boxes for the original castings in advance.  Good for using up excess RTV.Just cover the castings with excess RTV until next time you make another batch. Any type of carboard boxes will do, if you do not feel like making them

I have worked out many new ways to obtain clean castings for building front, that keeps the original master CLEAN. I don't use plasticine or rubber glue any more....Cover the back of the original with wide cheap masking tape. Then tape down onto a flat surface, such as glass or thin sheet metal.Build a cardboard fence ( mould box ) around the original. I use yellow glue, hold down for a few minutes and let dry.

Pour to the perimeter of the box first, and slowly work towards the centre.  The RTV finds it’s own level.Occassionally tap the box to help rid of air bubbles. It takes a few hours for the whole thing to set, so no need to panic during the process.These days, I can make up a cardboard box, mix a solution and have resin castings in one day.

Making the RTV moulds is extremely simple.

Drystone ( fine plaster ) for large castings, such as buildings, large drums.

Add  a small amount of water into a plastic container. Add Drystone to it until it covers the water, then mix.  It should look like "pancake" mix.A little water , makes alotta mix. Use a 1/2" brush to "paint" the Dystone into the moulds to start with.  Gets rid of most air bubbles. Then pour additional. Scrap excess so you get a flat casting.   Let dry and "pop" out the casting..   

Resin EASYFLO 60  was the key to a successful, highly detailed casting.  

Make small solutions, say 60ml total ( 2 part mix ).   This stuff cures quickly, but fantastic.

I do hope, no ever suggests making moulds or castings is too hard.   The first project of any sort is can be frustrating. 

It's fun, cost effective and rewarding.  Funny how the more we do, the easier it gets.

Keep a lookout for future updates.

22/3/2005