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Tuesday, February 15, 2011

Build by Poured Acrylic

Funny how they accumulate, all those bits and pieces saved as reminder of good times, important times, other days, other people. There are for example, the sea shells the kids gathered at the beach last summer. There's the big copper penny from pre-decimalization days. And the butterfly that is the pride of your doughter's collection. How about the ticket stubs, polished stones, brass button, locket key, bracelet charm. World War II medal, miniature doll - the list of such fragments is endless.

Fortunately, there is a craft activity that can transform these odds and ends into beautiful and charming objects. The technique is called embedment, and is not the same as that used to create the room plastic. This material is not the same as that used to create the room divider. The name is the same and the chemical formula is similar, but the properties are vastly different.

It is just this difference that makes possible a whole new list of craft items. In this form (and combined with other plastics), acrylic is a slow moving liquid that pours like treacle. When another chemical, called a catalyst, is added to it, the soft plastic turns first to a stiff jelly and then unique properties, you can embed in a transparent block all sorts of objects.

Although the plastic is poured in layer, one layer blends so perfectly with the next that you will not be able to discern the joint. This is craft work where a small investment in patience pays dividends because the task is easy, the praise high. Use stock materials when you try plastic embedment, and keep notes on how they work, to find the brands that produce the results you like best. Don't mix manufacturer's products; use basic plastic, catalyst, and additives made by the same company. Later may you want to try non-fracture additives, accelerators to speed hardening, and other magic chemicals.

Mold Making
Rigid acrylic sheet makes a fine mold. Cut sections of the plastic, and fasten them together, using solvent type adhesive and hollow needle applicator. To make certain the mold does not warp, reinforce it with wood strips underneath. Drill and countersink holes in the base. Drive in screw until heads are flush with plastic. Add more bracing at the corner or along the side of the mold whenever extra support may be support may be useful. If in doubt, always overbuild. The extra work is minor when compared with the task of trimming down a lopsided or bulging embedment.

Strickly speaking, molds are not tools. However, you will need them. To start. buy polyethylene molds in a craft shop. These are made of soft, waxy plastic. Casting readily come loose from them. Experiment with ice cube trays (the soft plastic type) for small embedments such as rock samples or insects. Glass jars can be used once, because you have to break them (gently) to release the casting.

Once small item that makes casting much easier is quite inexpensive, but you need a good supply -stirring sticks. You should have them in a series of sizes. Buy them by the box. Get orange sticks and tongue depressor for small jobs, paint paddles for big ones.