I was recently on a school field trip with my boys. While away, we
picked up a pair of fossilized scallop shells, top and bottom. I plan
to embed these in a clear, colourless resin, then mount them in a two
2-3" rimu slabs, with the top slab at about a 45 deg angle to the base,
mimicing an open scallop. I'm looking for some advise on a good
embedding resin to mount these in. I'm planning to brush in the first
few coats as the shells are rough, and I think will trap air bubbles,
which will detract from the whole look I'm trying to achieve.
Any thoughts would be appreciated.
Water-clear polyester embedding resin. You need to use the right resin,
but anywhere selling fibreglass supplies should have it.
It's usual to pour one layer first to form a "bed" then cure it
overnight. Lay the object on top in a position that allows it to vent
air bubbles, then pour the second layer over it. Carefully pour the
resin first into the voids to fill them. Use a wire to tease out any
visible bubbles. Getting the orientation right is usually enough to
avoid bubble problems. It doesn't matter which way is "up" if you're
going to polish the surfaces afterwards,
You can also tint the resin to make an opaque background (usually poured
last). Back in the '70s we'd embed seaweed or anything alongside shells.
Paper should be sealed with hairspray first, otherwise it tends to go
The resin cures tacky if exposed to the air, so either cover it with
polyester (Mylar) sheet, or do some sanding. It'll sand easily enough
with normal abrasives. Use silicon carbide wet and dry down to about
2000 grit (used wet) to get it clear, or else about 800 grit and then
paste polishes. Use a powered sander for this, because life's too short
to do this job by hand!
Moulds can be bought or made of anything with a good surface, even
silicone rubber. Candle moulds can work, but natural rubber ones need
careful waxing. You can even use one-off moulds in Plasticine. MDF with
a few coats of shellac is good, then apply proper release wax (from the
fibreglass supplier) before pouring. Rough surfaced moulds just need the
cast polishing afterwards, which is no big deal if you're already doing
the air-exposed surface.
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