New Developments in Leaf Making

Nicole has moved on back to her post at the Entomology Department and I now have another very able volunteer Stefan Hurlburt.



Stefan comes in every Weds and moves the leafmaking work by great leaps forward! Stefan has modified the casting process since a leaf cast with 100% five-minute epoxy is too flexible at the thin casts we are making. We found that another more rigid epoxy at Polytek, a 1010 epoxy with 1212 catalyst. The 1010 is too brittle, so we have found that mixing it 50/50 with five-minute epoxy gives us a perfect blend of not-too-rigid and not-too flexible for the leaves. Also, we have found that the wires that hold up the leaves can’t be too thin or the weight of the leaves will cause them to droop. All these little tweaks to the method are inevitable in the fabrication process.

The aluminum branch was a challenge in different ways. We needed to make the branch out of something rigid to serve as a “lifter” underneath the old, droopy leaf canopy. We had to span at least 36” out from the large maple tree branch, so we started with a ½” aluminum rod. We had to taper the rod over the 36”. I tried hanging it from the ceiling with a heavy weight on one end. I heated the rod with an acetylene torch. This has worked in the past with steel rods where I was able to taper the whole length of it by heating it with a torch. I wanted to stick with the aluminum to keep the weight down and ease the drilling of multiple holes for branches and leaves. The heated aluminum wasn’t as cooperative as the steel. It didn’t stretch and eventually broke off with the heat. Plan B then was to put the rod into a drill and, with it rotating, run it back and forth over the belt sander. This is a dirty process. One person needs to run the drill while another keeps pressure on the rod as it is run over the belt sander. Eventually, the taper can be produced this way, but it is hard, dirty work. We also broke three sanding belts tapering one rod.

Tapering the aluminum rod.

Tapering the aluminum rod.

Once the main branch is tapered, smaller forking branches are added. We produced these with ¼” tapered aluminum rod. These are no longer than 8” and are easy for one person to taper on the belt sander. At the butt end of each branch, the rod is turned on a small 1” belt sander to make a 1/8” nub that will be drilled, inserted, and pinned into the main branch. Actual sugar maple branches are used as guides to get the right placement of branches. It turns out sugar maples branch in pairs opposite each other off the main branch. After the smaller branches are attached, the main branch is bent 3-4 times to look realistic.

Aluminum branch

Aluminum branch

Small silicone peels are made from actual sugar maple branches. Auto body filler (bondo) is used to cast realistic texture and details onto the aluminum branch from the peels. Bondo is easy to sand and feather into the aluminum branch. Usually, there is a small bud remnant between the forks of two branches. These were made with a ½” pin with white glue and cotton string wrapped around it. Finally, I used a grey spray Krylon to finish it off. A note of interest: The original fabricators of the canopy used a solid grey color to paint their branches since the branch is in silhouette and no variations of color can be seen. Their painted branches are actual woody branches and it is a mystery why they painted them at all.

Stephan also painted the leaf petioles orangish-pink with acrylic paint in an airbrush. We initially tried using a brush, which left globs of paint. (I knew this was a bad idea, but I was too lazy to set up the airbrush!) Of interest: ANY paint that extended up onto the leaf turns opaque. Even the airbrushed pigment in light coverage starts to turn the leaf opaque. I experimented with applying Kremer dry pigments by brushing them over the leaf surface. While in a Medical Illustration program, we learned a method of illustration on paper called “carbon dust” where we ground down graphite to a fine powder and used a dry brush to apply it to our drawings. I have heard of other artists using this method with pastels. It turns out this is a good way to create blushes of color on the leaves and maintain the translucency!

Epoxy Leaves on the aluminum branch. Note small details between branches.

Epoxy Leaves on the aluminum branch. Note small bud remnant details between branches.

We fabricated a mounting system with sections of ½” plumber’s pipe mounted on a section of wood that was placed into a hole in the large branch extending out from the trunk of the tree. The branch had been made hollow with hardware cloth covered with plaster casts of bark, so a hole was put in for seating the mount out of view from the front of the diorama. The aluminum branches fit snugly into the plumber’s pipe and a ¼ 20 set screw holds it firmly.

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