The New Easy Mixing RTV Mould Making Rubber

At last a polyurethane RTV rubber that allows you to mix the Part A with the Part B in easy to mix equal quantities of each. No more endless, careful, time consuming weighing. Two plastic disposable measuring cups are required then pour in equal quantities of each part, mix together and pour!

The biggest handicap to using polyurethane has always the time it has taken to get to the mixing stage. Weighing has had to be accurate otherwise you finish up with a mixture of Part A and Part B that does not set. And you have to experience this to know what a horror cleaning a model can be.

We have named this new polyurethane moulding rubber CraftMold 35. It is our most popular and versatile rubber and can be used for mould making either by pouring or brushing. We have developed a thickening powder CraftThix that can be mixed with the rubber to thicken it to any viscosity.

After mixing the Part A and the Part B leave it to cure overnight to form a flexible, very strong RTV mould rubber. Polyurethane is not as stretchy as latex and moulds must be made with this mind. The majority of moulds we make with polyurethane have a seam down the side to allow for easy release.

How do we select which rubber to use? The easy answer is we use CraftMold wherever we can, due to its much longer life than latex. Latex appears to be cheaper but in actual fact the finished moulds cost about the same. As far as the finished moulds are concerned everything is in polyurethanes favour. We have moulds that are still producing perfect reproductions 15 years after they were made. No shrinkage, no deterioration of any sort, which is the reason they are increasing in popularity in the US particularly in the plaster and concrete industries.

The “35” in the CraftMold 35 name is the degree of hardness of this particular polyurethane rubber. It stands for shore 35 and is one of the softest polyurethane rubbers on the market. We find it of great use for the smaller plaster and concrete moulds which have either undercuts or a lot of detail

We have other firmer versions of polyurethane such as CraftMold 40 CraftMold 55 and CraftMold 75. These rubbers are mixed in different proportions to CraftMold 35 and are used where the higher Shore values are of use, such as for concrete stamping moulds and highway noise barriers, larger garden statuary and master moulds for ceramic pottery moulds.

Plaster will release easily from CraftMold as will waxes, making it of great value for the manufacture of candle moulds. Sculptors also prefer polyurethane moulds for the reproduction of busts and figurines. It also is widely for special film and stage effect reproductions and architectural work.

Polyurethane rubbers are considerably cheaper than silicone and outperform silicone in an increasing number of industries such as for its hard wear with plaster and concrete. However it is necessary to compare both rubbers very carefully when you make your selection, as silicone is still the easiest rubber to use because of its ease of release and inherent flexibility. If it only did not cost so much!

For information on purchasing Craftmold 35 click here.