Latex rubber is the cheapest mould making rubber to buy. Unlike silicone and polyurethane rubbers also used for mould making, latex rubber must be brushed on to your model in layers, allowing each layer to dry before applying the next coat.
This takes time, so the selection of a rubber can come down to the cost of the application of the rubber. If your time is your own, it is far cheaper to use latex for many mould making applications.
For many home or small businesses such as the garden ornament business, latex has always been the preferred rubber to us for the manufacture of the stock moulds. The results are equal to or surpass silicone or polyurethane moulds for use in this industry. During periods of low business activity, it makes sense to make your production moulds from latex, thus saving a considerable amount of money.
Water based latex is one of the simpler materials with which to make a flexible mould. Its ability to reproduce detailed surfaces is very good and the shrinkage is low.
Latex differs from the RTV rubbers such as silicone, in that it must be brushed on coat by coat to build up a suitable thickness. In addition each coat must be allowed to dry before the next coat is applied.
The big difference between a silicone and a latex mould is as mentioned previously, the time it takes to make the mould. The silicone costs much more than latex but the ability to pour the silicone over the model makes it much quicker to use. If you have the time to spare, latex is the preferred material.
The larger the mould the bigger the cost savings. However, when you are first starting out in a mould making and casting career, money can be important and this is where latex can be useful for moulds of any size.
To make life easy for the latex mould maker we have 3 types of latex available:
KwikMold Latex #70
* Pure 60% latex straight from the tree, just stabilised with ammonia to preserve it.
Pre-thickened latex designed to speed up the application of latex.
* For those applications where a non-drip latex would be of use such as making a mould of a vertical wall cornice.
To ensure maximum pick up of detail we recommend that you use KwikMold Latex #70 for the first 3 to 5 coats of latex. For ensuing coats and to speed up the application process use KwikMold Latex #72 which is the pre-thickened latex.
Allow the water in the latex to evaporate between each coat and leave behind an amber coat of natural latex. Latex will adhere to the previous dried coat of latex if applied reasonably soon, say within 24 hours of the previous application.
Brush on with a dabbing action and make a stronger mould by cross hatching each coat of latex. (Apply at 90⁰ to the previous coat)
KwikMold Latex #70
This is a natural pre-vulcanised latex using ammonia as a preservative. Left to air dry it will change from a milky white colour to its natural amber colour as the water evaporates. It can be used to spray on each coat on a model, thus speeding up the latex application process. It is used for the first 3 to 5 coats to ensure that all fine detail is picked up and be reproduced from the interior of the finished mould.
KwikMold Latex #72
This is a pre-thickened latex used for the final coats on a mould, speeding up the process of mould making. Each coat must be allowed to dry ensuring that no undried latex is left sealed in the latex layers thus giving weak spots in the finished mould. All up 10 to 12 coats are required for the smaller moulds and a total of up to 20 coats may be necessary for the larger garden moulds.
KwikMold Latex #74
This is a thick latex paste used for vertical type applications where the thinner latex varieties would run off the model. An example of this would be in applying latex to make a mould of a ceiling cornice. These rarely have fine detail and #74 can be used for the entire job.
#74 can also be used to build up thickness quickly on the backs of plaques or other flat backed objects.
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