This year, prompted by Lloydchoc's suggestions in this thread I purchased a copy of American Cake Decorator magazine of May/June 2003 to help me get started and worked my way from there.
So follow along and see what we have accomplished so far.
I started by obtaining the emulsion. This is the stuff that is applied to the screen. The American Cake Decorating magazine said to get Ulano TZ/CL (CL for clear) as it is food grade. In speaking with Ulano directly, they told me that while this is the one everyone uses for chocolate transfers, they have never gone to the expense of having it declared so by the FDA. Essentially it is a mixture of poly vinyl alcohol (PVA) and diazo dye. Diazo dye is light sensitive and causes the PVA to harden when it is exposed to light.
The first problem I ran into was that no one in Canada carried that particular emulsion so they would have to order it from the US. By the time all was said and done I was forced to purchase 4 - 4 litre containers of the stuff. Once you have mixed it up you need to use it within several months, so I poured off 1 litre, weighed out 1/4 of the diazo dye and mixed that. I couldn't help but notice that the base - the PVA - smelled and looked just like white glue. A little research online has convinced me that it really is just white glue, so right now experiments are underway to test this hypothesis.
These are pictures of my screen. It is an 80 mesh which means it has big holes compared to the usual silk screen. It means that your print won't be quite as crisp, but lots of coloured cocoa butter should get through.
The two sides of my 80 mesh 'silk' screen. Polyester actually.
I purchased the screen at Screentek, the same place I got the emulsion. Andria there gave me a quick lesson. Originally I had planned to expose the screen using a 150 watt light bulb as shown in the cake decorating magazine, but Andria convinced me that she had a great customer who lived on Manitoulin Island and she had already told her what I wanted to do, so I should go and visit her to expose my screens in the most professional way.
I stopped in at Bebamikawe Studios the first day I worked at the clinic in Wikwemikong. There I met Georgina, the proprietor. She is a graduate of the Ontario College of Art and runs a very sucessful business making signs, screen printing on fabric and other items, and embroidering traditional native designs on clothing, moccasins and various other items. She was rather intrigued with this whole chocolate idea, but was rather unclear about what a chocolate transfer was.
The following pictures are to illustrate applying the emulsion to the screen, this is Georgina at work. Note the even, smooth strokes. Nothing like my application. But like she said, she does have over 20 years experience doing it. This is actuallly the experimental emulsion that I made with white glue on one of her reclaimed screens.
The emulsion is poured into the applicator.
The emulsion is applied to the screen with the applicator in a thin layer. You do the flat side of the screen first then the raised side. In this way you end up with a thicker layer of emulsion on the side that will be down when you are printing. The emulsion then needs to dry overnight protected from light.
A couple of days before I went down to Wiki, Beth (Beth Wilson on eG) from the Manitoulin Chocolate Works and I spent the afternoon in her brother in law's print shop getting our images prepared. It is important that the image be crisp and clear and that the lines are thick enough to show up when printed. For example a flowing script that has a loop in a letter may not actually end up with a loop when you are done. I had Keith take the script from my label and rearrange it in a way that should print well. Beth had him take an image of Manitoulin Island and add the initials MCW for the chocolate works under the island.
Two transparency copies are made of the desired image and taped together to make the image as black as possible.
The image is placed on a table that contains some extremely strong lights. The frame is placed on top of the image.
The screen is placed over the image. Care must be taken in determining which way is up, you want to end up with a backward transfer so that when you apply it to your chocolate it is the right way around.
A vacuum is applied to the frame with it's attached transparency. This holds everything in place and minimizes extraneous light. After about 8 minutes under the strong lights, the emulsion has hardened and you are ready to wash the screen.
After exposure to the light a strong steam of water washes away the areas masked from the light by the black printing.
Now we were ready to try to learn to print our transfers. Beth and I taped a piece of overhead projector acetate to the counter and prepared the coloured cocoa butter. I mixed some melted cocoa butter with powdered PCB dye on a piece of marble. I worked it until it was starting to firm up but wasn't so stiff if wouldn't flow. I used the heat gun to warm it again if it got too stiff.
The coloured cocoa butter pool.
Note the tongue depressors taped to the frame. This holds the screen an 1/8th of an inch or so above the transparency so that it springs back after the squeegie is applied.
Getting ready to flood the screen with the coloured cocoa butter.
The initial squeegie to push the cocoa butter into the screen. Note that I am holding up the end of the screen that is towards me in order not to print on the acetate yet.
The final squeegie to push the cocoa butter onto the transfer.
Beth's transfers in blue. Very early on the learning curve as you can see.
Beth's transfer in dark chocolate.
My first attempt in blue.
The chocolates with the transfers still in place.
After peeling off the transfers.
My trials with gold coloured cocoa butter. After showing the dark chocolate and blue transfers to Georgina she showed me how she floods her screen for printing T-shirts. So on this attempt I dragged the squeegie over once to fill the script, then went back over it a couple of times to make sure there was lots of cocoa butter over the lettering. When I pushed down for my final squeegie application I got a reasonably good application. Of course you have to work quickly before the cocoa butter starts to firm up or your screen will glue itself down to the acetate.
There is a bit of a problem I have yet to sort out, the edges have more intensity of colour than the middles. When I get back home I'll take my screen and cocoa butter etc and head back to screentek and get Andria to watch my technique and give me suggestions.
This is what happens to transfers after the dog hauls them out of the box and licks each one to get the chocolate off. Not a single transfer escaped his tongue.
Total cost - $74 Cdn for 4 litre pail of emulsion, $22 for applicator, $17 for squeegies, $20 per screen. Cost for Georgina to copy our images on to the transparencies and expose them $55 for both screens. We could have saved $30 by printing our images to the transparencies ourselves.
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Posted 25 July 2007 - 10:14 PM
exciting discussions.
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