Surface coats look like very thick paint. They are the outer working surface of a mold and must be capable of picking up fine details. This is the material that is applied first when constructing a mold. The lamination or casting is made behind it. Once removed from the pattern, the mold surface that you can see and touch will be the surface coat. |
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Surface coats look like very thick paint. They are the outer working surface of a mold and must be capable of picking up fine details.
This is the material that is applied first when constructing a mold. The lamination or casting is made behind it.
Once removed from the pattern, the mold surface that you can see and touch will be the surface coat.
There are different types of surface coat for different applications.
If the end product needs to have a very shiny molded surface, then the surface coat must also be capable of being polished to a high gloss.
Conversely, if the mold is likely to need “adjusting” for the fit of the parts, a sandable surface coat that can go on fairly thick would be a good choice.
Yet another different application is that of what are called “trim and drill fixtures.” These may look like molds, but are used as a fixture or a guide for trimming molded parts to the correct size or drilling holes in specified locations. A surface coat for this application needs to be tough and abrasion resistant. In other words, very NOT sandable!
Applying a Surface Coat:
* Prepare the mold or pattern for molding. Follow the instructions for applying mold release.
* Read the instructions for the surface coat and follow the safety guidelines.
* Trim the bristles of your brush so that they are about ¾ inch long. Remove any loose bristles.
Alternately, buy pre-trimmed brushes from us!
* Using the proper mixing ratio (it was on the datasheet, dude..) mix a batch of surface coat that’s large enough to either A) cover the surface of the tool you’re making, or B) not so large that you can’t use it all up in the amount of work time that the material gives you, whichever is smaller.
* Using your specially prepared brush, apply a very thin coat of surface coat to the surface of the model. 20 mils is the thickness you are trying to achieve. Once completed, let the surface coat dry to a tack-free state (you can touch it and leave a fingerprint, but nothing comes up on your finger).
* Mix and apply a second thin coat behind the first. Allow it to become tack-free before moving on to the laminate or casting stage. |
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