I found 10 mil PETG from a company called Sabic Polymershapes. They cut the plastic to my specs so it is ready to use in my vacuform machine. Now, I have what I need to test the printing on the vacuform sheet itself. I also found the material, Vivak, that I was given at the AMNH is also 10 mil PETG.
This Friday, I went to Yale’s Digital Media Center to work with Ken Lovell. Ken demonstrated rolling out a couple of layers of a print-friendly substrate called Inkaid on the PETG, letting it dry, and then, running it through the inkjet printer. The ink from the printer adheres to the Inkaid substrate just like it was paper. Here’s a photo of the results.
Leaf prints on 11X17 PETG. Color saturation good with white background.
I inquired with Inkaid about the archival quality of the material and they assured me that it would last as long as the Epson inks, which are calculated to last for over 100 years! This is very good news for making leaves for the dioramas. I brought the prints back to my lab with the molds. I set up a vacuform box so I can test this process, one leaf at a time.
THE TEST: I was able to pull a pretty good cast, but getting the printed veins to line up with the veins in the mold was almost impossible. I had to try to move the hot acetate into place and had trouble with the plastic folding and sticking to itself. There is just so much the PETG can be moved around while in its melted state. Another problem is that printing on the clear acetate makes the inks appear less saturated. When printing on fabric, the white surface reflects the light back through to color in such a way that the colors appear about twice as saturated as on the plain acetate. This could be a problem, but Ken suggested I try a mixture of clear and white Inkaid substrates to produce a milky surface on which to print. It might be possible to get the same translucency and reflectivity of the fabric. Then, I would have to work on getting the print to line up in the mold. Ken thinks the shape of the 2D prints could be changed to fit the 3D shape of the mold by 3D scanning the molds and using some morphing software he has in the lab.
Ken also suggests I try printing on a subsurface made up of several layers of acrylic gloss medium or matte medium mixed with white acrylic to get a milky translucent “skin”. The acrylic medium is built up, layer-by-layer on a sheet of plastic, covered with another layer of Inkaid and the whole thing is run through the printer. The dried acrylic medium/Inkaid “skin” can then be peeled off the surface of the plastic and adhered to the vacuform leaf. This is esssentially another cheaper version of the fabric printing method. More work to be done!
George Petersen circa 1950s, Plant fabricator extraordinaire.
Autumn and I took the train down to the American Museum of Natural History (AMNH) to meet with their vacuform specialist, Beck Meah. We brought a couple of our printed vacuform leaves to show her what we are doing. We met her on the fifth floor of the Exhibition Department where the vacuform machine is located and got to “talk shop” for about an hour. The AMNH’s vacuform machine has a defective vacuum pump and they have rigged it up temporarily with a regular shop vac. Surprisingly, they seem to be getting good results with it! They use clear Vivak and sometimes a thin white (opaque) styrene instead of acetate or PETG. Beck said they bought a large amount of the Vivak years ago. She gave me a sample to try back at the Peabody. I put a vernier caliper on it and it is thinner by half! of what I am using. The PETG I use is .020” and the Vivak is .010”. She said that they are looking for a good glue to adhere the leaves to the wires, which is a problem I have, as well. I use B-72 and the results are less than satisfactory. Beck said they sometimes drill two small holes in the vein and snake the wire up and through the two holes to hold it mechanically rather than depend on the glue. She also said that in some of the dioramas the preparators would wire the leaves on top of the leaf if it was going to be seen from below to help hide the wire. We will use that advice when we make the maple leaves for Forest Margin diorama for that very reason. They will be seen from below. Beck uses extrinsic painting on the leaves and says that she can get an acceptable translucency by keeping the paint application light. I believe her because Tomy Newberry and Gary Hoyle, two preparators I have great respect for, both said the same thing to me. That said, I have found that any paint on the surface reduces the translucency and I am sure the old-timers knew this and struggled with it as well. I walked through the African biodiversity exhibit, which opened ten years ago or so to assess some of the more recent leaf work. I found the leaves to be mostly opaque which therefore gives them (now that I have been mentored by Ray deLucia) an unsatisfactory plasticky look. The form was good because they were vacuformed, but the realism was lost to some extent because of the opacity.
At the AMNH, they make plants by soldering together brass branches and adhering the leaves afterwards. I learned to make plants by making the leaves and gluing on the petiole, or leaf stems, first and then wiring them together afterwards using shrink tubing and epoxy glue, building the plant from the top down, adding more leaves and branches as I go down. With this method, I get rather lumpy branches that need attention to get them to look realiastic. This other way might save time. Beck said that there is a soldering tool sold at Micro Mark that can solder small brass wires to thicker stems with just a tiny bit of solder. That sounds like a useful tool to have around. This is why I love to talk to other museum preparators!
Tomas Newberry, circa 1957, Foreground of the Redwood diorama.
Autumn and I left Beck and walked down to the Olympic Rainforest diorama to look at the leaves done in the early 1950s by the legendary foreground preparators, George Petersen, Fred Jalayer, and Tomy Newberry. We were blown away at the attention to detail, the translucency, and the realism everywhere we looked. This level of quality probably can’t be recreated today. George Petersen made leaves for his whole career at the AMNH. Forty years of honing one’s skills just on leafmaking is hard to match by us generalists!
I am working now with Autumn Von Plinsky, a recent Yale Art School grad, on this project and this week we got another type of leaf produced, a maple leaf.
There are still some problems, but there is a lot that is working well. First, the problems: The detail of the leaf is compromised by the printed fabric, but only if it is adhered to the bottom of the leaf, and also by the wax coating. This method sacrifices some of the surface detail of the veins and subtle texture of the leaf for a strong graphic quality. The excellent surface detail is typically why leaves are vacuformed in the first place. Another concern is the quality of the ink used in the printing process. How colorfast will they be? This will have to be researched before any of the new leaves are placed permanently into the dioramas. The selling point of this method is that it is fast, there is no need to paint detail, which in this case could take hours, and the leaves are strongly translucent.
I have yet to put these leaves into the diorama, but I think they will read well and the graphic quality will carry them. Ideally, we might be able to develop this to get both the texture and the graphic qualities.
Autumn found out that one of the graduate students in the Yale Graphics Program is printing on acetate and vacuforming over three-dimensional objects. There is going to be a presentation about this method on Nov 8th. We will be attending with the hope that we might be able to use this process to vacuform printed acetate leaves on our plaster leaf molds. If this works we might be able to achieve a leaf that is quick to make and has the subtle texture of a real leaf.
I went down to look at the exhibits in the American Museum yesterday. I focused on the Warburg Hall (1951) and the North American Hall of Forests (1959) to see some of the work of the really great foreground artists from the 1950′s, guys like Tomy Newberry, Fred Scherer, George Petersen, and Fred Jalayer. Newberry is still alive and I talked with him on the phone last week. I mentioned that I was really impressed by the work I saw in the Warburg Hall, mentioning specifically the lady sliper flowers. This summer, I walked through the hall with a retired educator, Bill Schiller, who pointed out that the flowers were so accurate, that he could teach schoolkids about how pollen gets stuck to the back of bees when they crawl into the flower. He can show the flower structure that does this from the model.
Newberry said that they were quite dedicated to the work. They pushed each other to do good work, even to try to outdo one another. Here are some maple leaves from the Olympic Forest diorama. These are exactly what I am trying to get with my quest for translucency in leaf fabrication. I hope they are not made from paper, because I think it is only a matter of time before they will start to curl.:
I also saw some work that was of very high quality, but made with paper and starting to curl with age. The Warburg Hall and the NA Hall of Forests are long overdo for a cleaning and renovation. Unfortunately, they will probably be torn out at some point in the near future.
Beautiful work, but look closely at some of the leaves. They are curling up.
Poly silk print on vacufom leave. Colored wax over all.
Using a print on “Poly Silk” adhered to the vacuform leaf works very well (Thank you Sally Pallatto for the idea!). I use a dilute solution of B72 to wet the poly silk and it conforms almost on its own. The fabric adheres to almost all of the curves and forms of the vacuform leaf. I found that it works better with less air bubbles if I adhere it to the top side of the vacuform leaf rather than to the side with the impression of the veins. After the glue dries, I dip the vacuform leaf with print into colored beeswax, shaking off the excess wax. I’m going to do more tests on this method, but I am close to being ready to make a large run now.
I’m running into some problems with the Gerber prints. Whereas the prints worked well for the mostly flat Meganeuropsis wings, the vacuform leaves have enough variability that I can’t get the prints to conform to the surface without cutting into the print many times to get it to flex over the surface. When it doesn’t fit snuggly to the surface, bubbles appear, so bubbles and problems with too many slices into the prints are the down-sides of this method. Nonetheless, I am encouraged by the realistic detail and translucency. The Gerber prints have the color embedded into the print which gives the translucency. If I can get the color right, and can find some way to prevent them from curling, there will be little to no need for extrinsic painting. These leaves may work in the diorama, but I want to get it better first.
Too many bubbles visible
Too many bubbles and slices in the Gerber print
Sally Pallatto, our graphics artist, and I met this morning to send off a “leaf” file to a printing company that we used in our last exhibit to make translucent “scrim” banners as a design element in the exhibit hall. We discussed using fabric prints of the leaves rather than the Gerber prints to adhere to the vacuform leaves. Sally is pretty sure that the fabric will flex better to the leaf surface than the Gerber prints. The translucency should be comparable to paper which has been used for years to make leaves. If I can get them to adhere without bubbles to the vacuform leaves, then I think I will be close to solving the problem. Also, I have been finding that when the leaf prints are dipped in the colored wax, the detail is diminished by the wax, so Sally lightened the files and added contrast to pull out the veins a bit more. These new fabric prints should be arriving at the Peabody early next week and I will start a new run of leaves using them!
I have a full vacuform machine that can vacuform sheets of acetate up to 19″X 28″. I am doing some R&D on making leaves (see previous blog entries) and I didn’t want to make up full sheets of leaves, at least not yet, until I can get a good system developed. So I took my individual mold, drilled air holes around the leaf and up the stem. I then drilled a 1 1/4″ diameter hole about 1/2″ deep into the mold from behind. The hose of my vacuum cleaner fits snuggly into this. I used a cutoff disk on my Foredom tool to join each of the drilled air holes to the larger hole.
The bottom of the plaster mold
I lay the sheet of acetate on the surface of the mold, turn the vacuum cleaner on, and using an industrial heater, I melt the acetate, which gets sucked down onto the mold. In this case, I have to switch the vacuum in the middle of the process to a second hole to get the whole leaf. This works well to get one leaf and can be done cheaply without having to buy an expensive vacuform machine.
UPDATE N0vember 25, 2013:
I have found that the above system for vacuforming doesn’t work as well as making a small box with a hole drilled in the bottom to the diameter of the vacuum hose. The individual leaf mold is laid into the box, acetate laid over that, and heated while the vacuum is on. I made the box 6 1/2″ x 7 1/4″ (ID) and as long as the PETG acetate covers the entire surface while heated/melted down, the suction is strong and I am able to get better vacuform casts. here is a photo:
New vacuform box with leg for using in the vise and perforated aluminum platform.
Plaster mold of a red osier leaf and a vacuform cast from it.