Thoughts on this two-part composite mold workflow?

[helix_3]

I have a hypothetical two part mold, with geometry that prevents the user from being able to reach inside and hand-apply fiberglass at the seam. Assume it's a large mold, 24"+ wide, etc.

I'm assuming the foam backing is necessary because the green resin is creating a resin-only seam between two knife-edges of stronger fiberglass material, and represents a major weak point in the piece.

Does this method make sense? Is there any better way to do this?

 

[lmgill]

Mannequins are often sealed with a "flow coat" of resin and filler (thin Bondo)
This material is poured into the open mold, and the mold is closed and then rotated along the seam, to coat the seam with the thickened resin.

 

[helix_3]

Mannequins are often sealed with a "flow coat" of resin and filler (thin Bondo)
This material is poured into the open mold, and the mold is closed and then rotated along the seam, to coat the seam with the thickened resin.

That last post of mine was just to better understand how foam works, the current project is a ~5' tall version of this robot. The two-part mold would be for the arms and legs. I wouldn't be able to rotationally cast anything because my epoxy sets too slowly, and it would also be tricky physically rotating around molds that large.

Edit: I misread your comment at first- what you're describing would probably be a good way to beef up that back seam. My current epoxy is fairly thick, but I could probably find a thinner epoxy that would flow for that step.