How should we finish the pattern?

I have to admit that finishing has never been my favorite job when building an rc-model: everything is ready to maiden and extra time has to be invested „just“ for protecting the surface. This is one reason why I have done many of my maidens without a finish, besides that repairing a finished model is much more elaborate. Now, I have no other options than learning about two component paints and using a good spray gun.

The pattern of the center section is almost ready since a couple of weeks. „Almost“ because it has to be finished before creating a mold. The surface of patterns has to be in general at least as good as the one of the final parts, as these are usually painted directly in the mold before lamination to avoid excessive weight. Thus, any defect of the pattern is transferred almost directly to the final finish. Though the molds can be sanded and polished to a certain degree, it’s best to have a perfect pattern.

Finishing the pattern turned out to be more subtle than we thought before. We have been testing some techniques and decided to use a HVLP spray gun with clearcoat used normally in finishing cars. This should provide a clean and even surface suited to create a mold. However, not only the coat is important for the final result, but also the layers below.

The pattern has a wooden surface with many smal pores and cracks. Priming this surface would inevitably result either in a bad surface for the clearcoat or in having to spray and sand repeatedly. We, thus, decided to use Ahrweitex Schnellspachtel to fill the pores. This is a sort of one component filler, which is soft and gives you plenty of time to spread over a large surface with a spatula.

Here’s an example of two similar surfaces after priming. On the left without and on the right with Ahrweitex:


I think this picture speaks for itself.

We filled this way the surface of the pattern:


Soon, we will spray gun a two component epoxide-primefiller and a clearcoat from Mipa SE. I hope to get a great surface and good separation when producing the mold…