Tooling Gelcoat

Tooling gel is the special gelcoat used for making molds.. more heat resistant for multiple pulls off the same surface etc.. im sometimes not so good at explaining so heres a few snippets off the net..

“High abraision resistant gelcoat for production composite mould surfaces. Bright orange coating enables applicator to ensure adequate coverage has been achieved on subsequent gelcoats when making parts from the mould.”

And

“The main reasons for using tooling gelcoat versus finishing gelcoat have to do with the hardness of the finish and the shine of the finish.
The finished surface of your mold should be abrasion resistant. Polyester gelcoat is used for making tooling masters and molds where good gloss retention of the surface is of paramount importance. A high gloss finish of the molds surface allows for easier release of your parts and thus extends the life of the mold.
High gloss finishes produced by tooling gelcoats are less porous than the finish of typical finishing gelcoat. The porous nature can cause parts to stick inside the mold causing release issues that range from difficult releases to completely stuck parts.
The idea is to make the surface of the mold as slick and shiny as possible. Surfaces that are slick and shiny have fewer peaks and valleys on a microscopic level. Less peaks and valleys on the surface of the mold will equate to a decreasing chance of the resin or finishing gelcoat used in the construction of your part from biting into the surface of the mold and sticking.”

^^^^ Borrowed from [https://www.miketrax.info] who actually has some awesome write-ups and tutorials on his website.

Basically, thats why we use tooling gelcoat for molds. Besides the fact thats what it was designed for :-/ lol. It is much harder, less flexible and more resilliant than normal finishing gelcoat, and is much better at standing up to repeated cycles of the exothermic process as parts cure inside the mold. I will admit i have used normal finishing gelcoat to make a quick mold that i knew would only need 1 or 2 pulls or say a quick copy of a factory panel that is going to become a plug so the original doesn’t have to be damaged/cut/modded/etc. . Id slap up a quick mold with finishing gelcoat, but i would never do the reverse and make a part out of tooling gelcoat because, well, besides the fact tooling is more pricier than normal gelcoat, its a waste.. 90% of moulds i have seen have been the red/orange tooling gel, however i have also seen green tooling gel as well, and i think there is a black as well.
But if i am making a proper mold i would never use anything except tooling.

With tooling, brushing should be brushed, and spraying should be sprayed. For example. Resin or gelcoat can be thinned slightly to spray [with styrene or acetone] but with tooling it is not really recommended to add any sort of styrene/acetone products to the gel as it will screw with the chemical properties of the gelcoat [but if you MUST, no more than 10% for styrene and i wouldn’t go NEAR tooling with acetone, lol, are u asking for trouble?] So i wouldn’t bother trying to thin brushing for spraying, or spray brushing because its too thick.. [not forgetting the usual pot of acetone next to your spray gun, i have found tooling is much hotter than resin, and a fair bit more hotter than even normal tooling gelcoat, so remember to clean the gun as soon as you are done, because if it cures all inside the gun the tool will pretty much be written off..]

For molds i have always preferred to spray but now i am a bit partial to both.. brushing gives a nice thick coat but it is more messier and spraying just gives a nice clean finish, but with spraying to ensure coverage i would do at least 2 dust coats so the gel, when i did hook it on, had something to bite into, and the last layer of gel i would spray pretty thick. However the gelcoat shouldn’t be too thick, as then it will be quite brittle. Tooling gel shouldn’t be catalysed at more than 2.5% either as this can also cause shrinkage.

“CAUTION: Do not allow tooling gel coat to cure completely as it may shrink and pull away from the plug. This means you should never leave tooling gel coat overnight or over a weekend without first laminating at least one layer of fiberglass. This is the most critical step.”

[so i know most of this post is like don’t do this don’t do that but I’m a pedantic bish when it comes to moldmaking sooo.. ... and the tooling and first layer down is crucial, the most important part i believe lol]

Some of my ocean of red.. =^-^=

after a spray session (see my kitty in the dust in the background!)

the pinholes you can see are where it was a bit thin - issue rectified before initial layer was laid

Kenj xx