Hello folks,

Not an expert by any means here and looking for the best method to complete a project I have been given in work please.

Basically I have been given a small 400mm square piece of PIR foam (40mm thick) to layup with a few layers of fibreglass and then encapsulate in gel coat. The piece is to be used as a hatch for an exit and will be visible on both sides.

We have CNC facilities in work however I am unsure on how best to achieve the encapsulation and the correct steps. My initial thoughts are to coat the bottom part of the mould with gel coat then once cured layup with fibreglass all over. Afterwards I was going to pour the gel coat to flood the sides of the mould and over the top part of the panel and simply let it cure.

I am aware that there will be a join in the gel coat and guess I can buff this back?

Any advice would be much appreciated please. I have looked around and cannot find any projects similar to this. I will take some images when I tackle the project, a video if possible too.

:-)

How many layers of glass and what weight of glass... don't know, depends on if anyone will step on it. Experiment.
Lay the fabric on the sides +/-45° so it will go around the corner easier.

The following is pure speculation as I have never done this. Others might come up with much better ideas.
If perfectly straight and optically perfect surface layers are desired apply gel coat to a glas or similar flat surface, lay up or infuse two thin sheets on the gel coat and then glue these surface layers while still on the backing plate on the foam core, trimming the excess afterwards. For the gel coat I'd use the stuff that's usually used for glider aircraft, it's a polyester called T30 or T35, is available in white, can be polished to a high gloss if desired and epoxy adheres well to it. It can also be applied in excess to cosmetic repairs and then sanded down, e.g. on edges and corners.
As I said, others might have better ideas, I'm mentioning materials I know and have worked with.