Tips for Cutting and Joining Imitation Wood Mouldings

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Polystyrene MouldingsWorking with imitation wood mouldings is different than working with real wood.  Imitation wood mouldings are made of polystyrene, a dense plastic that looks exactly like wood but cuts somewhat differently. 

Polystyrene can melt when cut with a power saw.  The kind of melting were talking about here won't be dramatic or disastrous but it will present a minor hassle.  Usually when polystyrene melts, the melting is manifested as a burr along the edge. 

Cutting Imitation Wood Mouldings with a Power Saw

When you first remove the moulding from the saw the burr will be moist and pliable.  Don't try to remove it yet.  Wait until it's dry, usually a matter of about 15 seconds.  Then it should be brittle and break off easily and cleanly.

To avoid this burr move the spinning blade through the moulding quickly.  A quick, punching stroke is best.  As a general rule a blade with fewer teeth (40-teeth) will generate less heat and is favored by those cutting polystyrene.  However, many framers use an 80-tooth blade with no ill effects.  Make sure the teeth are not bent.  A single slightly bent tooth can cause melting issues with polystyrene. 

Cutting Imitation Wood Mouldings by Other Methods

Imitation wood mouldings can be cut easily in a manual miter saw which produces a nice clean edge.  For those experiencing issues cutting it with a power saw, this is a good low priced alternative.  Polystyrene can also be cut effectively in a guillotine chopper.  Polystyrene can be sanded in a manual sander like the Logan Precision Sander, but should not be sanded with a power sander, which will melt it.

Joining Imitation Wood Mouldings 

Imitation wood mouldings cannot be routed for T-nails, so the slot and peg system common in joining wood sectional frames cannot be applied here.  Imitation wood frames are best joined by clamping the four sides together in a pony band clamp after applying Plastibond Poly Glue.  V-Nailing is possible but not absolutely essential when joining these mouldings.  Many framers just use the Plastibond glue, although adding Logan V-Nails does not deter in any way and does  add strength to the frame.

These are some important considerations when working with imitation wood mouldings.  Bear them in mind and you should be able to get good results cutting and joining them. 


See our selection of imitation wood mouldings in lengths to cut and join yourself