Sunday, June 3, 2012

Heron sculpture gets a mold mother bird feeding young

I am making a mold of the heron sculpture from earlier posts. It will be cast in bronze.  The leaves were made separately from the heron so that they could be molded by themselves.  Much easier than trying to mold them with the heron.
 The heron's head feathers and left leg are removed and will be cast separately as well. 
 The leg is mounted upon a board.  The center of the leg is a wooden dowel into which a hole was drilled just smaller than the screw onto which it was placed.

 The tiny head  feathers are tricky.  I used a pin (the kind with a plastic ball at one end) for each feather.  I drilled a hole just big enough for each pin, pushed each pin into the hole and then carefully stuck the feathers onto the pins.
 The heron and leaves will get covered in a rubber mold material called Polygel 40.  There are 2 parts - A and B -that are mixed together in equal amounts.  Each goes into a cup and then those get stirred into a 3rd cup and when they are thoroughly mixed are applied to the sculpture with a brush.  The trouble is that the mold material tends to be messy.  Part A in particular is bad, the consistancy is like honey and it seems a lot drips out of container while pouring and ends up on everything.  So this time I am trying ladles to pour into each cup - it works very well, much cleaner and a lot less waste.
 Everything gets 3 layers of mold material.
 Then the shims are attached.  These establish the part line of the mold.  In the past we cut the shims after the mold material was applied and the job was extremely tedious.  For this mold I cut the shims a couple days ahead  (using a full size photo of the piece) so the shim attachment was much easier. A little trimming was necessary but they went on very quickly.   On past molds pins were used to attach the shims but here a filler material is mixed with the Polygel to create a thick, sticky material (the very light substance at the base of the shims). This made attachment much easier too.
 Shims attached to the heron.  I wrote each section on the shim so that I would know where each piece went without having a puzzle experience.
 Nearly done - jsut 3 more passes with mold material and it will be ready for the mother mold (a plaster outer mold to prevent distortion)
The reason I feed birds this time of year - a mother Titmouse feeding her nearly grown youngster.  The mother gets a sunflower seed,  painstakingly hammers it open, then goes to feed her young.  She has several perched through different trees.  The young flutter their wings and make begging calls while she opens their seeds. I'm sure it's a big help to mother birds to have a big container of snacks for the kids.

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