Making Moulds: Spheres for Pearls with Transparent Silicone
Sphere Mould Making Tools
Mould making spheres is very similar to charm bead moulds but I think a little less complicated, so I’ll do a separate post for those and another one for flatbacks and cabochons. You can download or pin a printable version of our silicone types here:
To prepare your mould masters (the bit you pour the silicone into) you need a few supplies. I use 11mm
stainless steel shot but you can use 3/8in (9.5mm) or 10mm. A few mm makes a lot of difference and it’s up to you and your clients what size to go for. Anything under 8mm can be hard to work with but you could go as low as 4mm for very tiny resin pearls for earrings, which you can glue onto earring posts (they tend to be about 3mm). I recommend getting a digital calliper for high end jewellery for mould making.
You can skip a lot of the work here by cutting out little circles of double sided tape and popping the sphere directly on top but the trouble is they tend to move around, and because the silicone around the hole is very thin it can tear easily, no matter how tear resistant your silicone. I like to secure the spheres on a little platform that’s the right width and height. It’s a bit fiddly but worth the effort for a decent mould for high quality jewellery.
I find any bubbles in my resin come up into the pouring spout with a little persuasion (more on resin another day). For this you’ll need plasticine! Raid your kids’ craft stash or buy some but trust me, Playdoh won’t work. It dries out and the same goes for other mould making clay. Blu Tack is too hard to work. You could try an oven bake polymer clay like Sculpey if you have it, because it won’t dry out, but I think plasticine is a little less expensive.
Using Plasticine in Making Moulds
I take a piece of label backing, because we get through tons of it with our shipping labels and order notes. It’s totally non-stick which helps when transferring the little “dots”. Roll a piece of plasticine out about as thick as 5 playing cards. Precious metal clay artists probably have those already taped up, everyone else don’t worry about buying cards, you’ll find the perfect thickness as you go or you can just get a cheap adjustable rolling pin. Using a stainless steel hole punch you can cut out the little dots (push them out with the end of a thin paintbrush). Cut out as many as you need then prepare your 20ml plastic shot glasses (it’s really important to get the 2cl or 20ml plastic ones, especially if you’re using the expensive water clear silicone, because a 30ml container will need 10ml more resin. If you’re making 20 moulds, that would be an extra 200ml or 7oz or silicone. I prefer not to have too much silicone in my moulds because it gives me a clearer view of my silicone cast and the finished piece is easier to remove.
If you’re making larger than a 12mm pearl mould then you might need a 1oz/30ml shot glass, and for larger spheres for making orbs and paperweights my advice is to save up yogurt pots or ask on your local Freecycle. If you’re making different size spheres it can be helpful to mark them in some way. Some mould sellers, I’ve heard, mark their finished moulds with Sharpie but this quickly rubs away. When I sold moulds I liked to use a tiny bit of plasticine to press a number into the bottom of the shot glass. If you wanted you could look for little sticky foam numbers, or just use tiny dots. I used to use a single dot on the side of my own donut shaped charm moulds. Now I don’t worry because they’re the only kind I make, but we’ve just started using 11mm spheres as standard instead of 9mm and my new 11mm ones I’ve made for this blog I used a pair of pinking shears to cut the bottom so they look different to my 9mm moulds. Pinking shears are great for making cloth baby wipes and family cloth from rags and have saved me a fortune over the years…
Give your sphere a good polish with a lint-free polishing cloth like these then use a pair of long nose jewellery plies to grip it firmly, place it on the plasticine dot and without squashing it down to hard, transfer it to the shot glass.
Please see our next blog about silicone to learn how to calculate the silicone volume, weigh, mix, de-gas and pour, and how to finish the moulds off.
Using Sphere Moulds To Make Pearls
You can see my own pearl designs here and I’m happy to give anyone advice on finding their own, unique way to set their finished resin pearls but I ask you not to copy mine too closely!
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mould (UK) = mold (US) thanks for the heads up Robin! Mwahhh x
calliper (UK) = caliper (US)
jewellery (UK) = jewelry (US)
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