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Learning to Cast in Resin

It’s not only wood that I make pens from. There are a whole host of acrylic and polyester resins out there that give a massive range of colours and patterns to choose from to the wood turner.

The idea is that a mould is made either cylindrical or rectangular into which the resin is poured. It then sets and then left to fully cure for a few days before it can be drilled and turned on the lathe into a pen or whatever you want.

Now, I don’t do things the easy way…I never have, so I have made some moulds which will hold a decorated pen tube with the resin poured around it. Easy eh? Well, it’s not that easy!

As an experiment, I made some moulds, decorated some brass pen tubes and then cast the resin around them to see how they would turn out. The pen to the right has been decorated with Viola flowers. When it came out the mould after being cast, the petals had faded, and this was down to the exothermic reaction of the resin setting. In other words, when the resin sets, it gets hot, and with unprotected natural things like petals, the colour fades. Next time, I will have to protect the petals with a layer of resin before the final casting. Hmm. Not ideal, but in the quest for perfection, patience is required!

The casting process is important as you need very few or no air bubbles in the mould at all, and it is in how the resin is poured that is the key to this. Firstly, you have to mix the resin and catalyst together in the right quantities to ensure a good, solid cast. Too much and it might get too hot and crack, not enough and it may never set at all. After it has all been very well mixed together, there will be air bubbles in the mix for sure. So, the key to a good, bubble free pour is to do it from height in a very thin stream so the bubbles escape as the resin dribbles into the mould. There will still be some bubbles in the mould, but what I have noticed so far, is that they escape as the resin sets. The image to the left shows the shell pen in it’s mould with the resin cast around it.

After 24 hours, the cast is ready to be freed from the mould and it will either fall out (as the resin shrinks slightly in the curing process) or can be persuaded out with a little tap. It should then be left for a few days to fully harden. However, conversely to waxes, resins harden from the inside out, so the cast should be ready to turn in a further 24 hours.

Casts can be brittle, so they have to be turned carefully into shape before sanding them down to finish them.

With all of my glossy, shiny finishes on pens, the item is sanded down to 1000 grit papers, then sanded further with wet and dry pads down to a whopping 12,000 grit and finished with an abrasive cream for the glass-like look and feel.

Here is how the shell pen turned out.