Preparing waxes for investment

Lester doing wax work

body sections, some with sprues added

wax heads and arms

The past two weeks Lester has been using the molds we created from the clay figures. He is brushing wax into the molds to create the hollow wax copy of the original sculpture. The red tubes you see in the pictures are wax as well. The red wax creates a system to introduce bronze into the pattern (sprues)  and to evacuate the air as the bronze is poured in (vents). I have been sculpting the patterns for the details, badges and shirt patches.

Polytek Spray mold system

Removing metal shims, you can see the flange dividing the figure in half.  After this step we sprayed on the rubber mold material.

Here I am prepared to spray on the plastic mother mold. Note two red pegs sticking up on the figure. Lester had the idea of using rubber grommets embedded in the plastic to help facilitate removal of the mold.

Spraying action shot. The loaded gun weighs almost 15 pounds. It was worth while to build the figures to be able to lay them down horizontally. Much easier to spray down and much less over spray.

Lester using air pressure to help release the mold.

Mold sections, even though we used air pressure to release we ended up peeling clay off the armature. Actually , this works very well as it's easier to reclaim the clay.

Of the 20 molds we made this way we only broke one. The plastic material was easily repaired with a 2 part epoxy made for plastic repair.

The face after peeling off the mold. This scrapes off the ears and damages the figure. No matter the molds are perfect.

These are photos of  the female figure taken over the last two days. It shows how we are using the Polytek Spray Mold making system.

A more feminine Deputy

A much less bulky body, thinner face and more friendly expression although the harsh light hitting her face isn't the most flattering. Her pony tail doesn't show here either. If you look back in the blog the difference is apparent.

Thank you Polytek

Molds are now finished on the male officer. The Polytek mold system worked very well.

The back half of the figure with the plastic mother mold sprayed on.  When we are working on the female figure I will try to get a volunteer to take some pictures of that process. With the two of us we can't take action shots, just too much going on.

Lester trimming the flange with a jig saw.

Lester holding the first section of mold peeled off the clay,

This shows a mold section, blue is flexible rubber, white is the plastic mother mold

All the molds fastened together with bolts. We drilled through the flange before peeling the molds apart. I managed to manhandle one of the molds and broke off part of the flange. No worries though it will still work just fine.

Stripping the clay from the armature. We save the clay for the next project.

The other side of the piece.

The arms set up and sprayed with the rubber.

This morning we sprayed on the plastic mother mold over the front half of the mold. That material goes on very quickly and sets up in a few minutes. We flipped over the sculpture and sprayed on the rubber material on the back half and sprayed the arms. Don't tell Lester but I forgot to spray release agent on one of the arms. That oversight will make getting the rubber off the clay a chore but won't hurt anything but my reputation. The rubber will cure overnight and we will then spray on the plastic mother mold.

I definitely am glad I went through the trouble of making these figures sturdy enough to lay them down. It made spraying them much easier with far less wasted material. The shop stayed cleaner too. The gun loaded with spray material weighs about 15 pounds. It is very tiring to hold up for several hours at a time while working.

Polytek Spray on rubber molds

Lester holding arm after we cut it off.  We tied and taped off the arms to keep  from deforming the surface.
This was a very stressful operation but worked out perfectly.

Figure without arms. This makes mold making easier and allows for better results,

Figure laid out to facilitate spray on mold. We supported figure in the middle to keep from deforming it.
We added shims to part the figure in half but I forgot to get pictures of that step.

After spraying, the tool in the foreground is used with cartridges for applying mold material.

Mold material applied, note the flange surrounding the figure creating a parting line for two halves of the mold.

Tomorrow we will be spraying on the plastic mother mold which will give form to the flexible rubber.
This was a stress filled day of very hard work. Everything worked as planned and tonight the rubber is curing so we can proceed to the next step.

Modeling hands in clay

That's me working on hands today and a close up of one that is finished.

Yesterday Robin from Duluth Police Dept. and Steve from St. Louis County Sheriff's Dept. came up for a preview. They are happy with the progress and gave me the go ahead to start mold making.

Lester has been making molds already of the hardware that goes on the officer's belts. The goal is to have both the figures finished and in molds by the 4th of Feb.