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Wood molding casting Answered

Need some ideas:

I have an antique wooden chest of drawers. Most of the wooden molding around the top and bottom is long gone, BUT I do have two original sample pieces. They are a pretty intricate design and there is no way I'll find anything like them today. So I thought I'd make a mold and cast some to replace the missing wooden strips. I smeared up the thin wood strips with Vaseline and pressed them into plaster of parís. Well the mold turned out fine, but now I am struggling with what to use for a casting material. I tried plaster of parís, it was to fragile. I tried painters caulk, but it was too flexible and looked like heck. Thought about mixing sawdust and glue, but am pretty sure the texture will be wrong and grainy. It needs to be stain-able so I can make it look like it's wood and semi rigid so I can get it out of the mold. Any suggestions??

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john043 (author)2018-01-27

Thanks for your thoughts. After I typed it, I have had another idea (hair brained?? ); mix some sawdust with water, wood glue and flour. The flour will settle into the mold and smooth out against the bottom of the mold so I have a nice smooth finish. The resulting trim strip, assuming I can get it out of the mold w/o breaking, it should be paint able as you suggest. Plan B would be as you suggest go online to see if I can find a commercial resin based mix.

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Downunder35m (author)2018-01-26

First it was not a good idea to vaseline on the wood ;)
Secondly it makes removing/filling damages on your original next to impossible now.

Anyway: consider making a silicone mold, plenty of Intructables available on the topic and the oiled wood will be a good candidate for it now too.
Plaster of paris can be perfect for a mold if the original is perfect, removing material or adding it to fix imperfections is very hard once vaseline is used.
A silicone mold can be washed to remove all traces and if careful you can use solvent based fillers on the wood to fix it if required.

As for the filling material....
I had quite good success making my own particle board based creations.
But to avoid shrinkage it means getting the mix and moisture content of the glue wood mix right plus using vacuum sealing...
You might want to consider a resin based mix especially if you can get resin that can be thinned with acetone or similar.
Here you can pre-soak the wood particles to allow a better resin prenetration and shrinkage can be minimised by allowing for a rim around the mold so the bottom of the pice can be sanded off until flush - this way it should mostly shrink like a flat funnel in the center.

To get a wood like finnish....
Take a look at vidoes showing how to use acrylic paint on a water surface to create everything from simple circles to faces and landscapes.
With a bit of practice it is easy to use two colors to create a random looking wood grain patter that you can transfer onto your finnished piece.
Require practice, patience, a steady hand and very good preparation of the workpiece!

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