Varnish heat tank and ‘helper tray’ for 12×20

So last night it was driving me nuts while I was in bed. Lying there thinking about the varnish and the evenness of developing on the big plates and just lay there brainstorming. Then I picked up my copy of the Silver Sunbeam (the original wet plate manual) and started reading the section about the varnish…

Interestingly, Towler writes that the sandarac varnish should be applied to the cold plate. It does not suggest heating the plate up for the varnish. Why this is, I don’t know. I did a bit of reading online and it was theorised that perhaps it was for events where people wanted to take their tintypes home with them immediately and the step of heating and curing the plate over heat was too risky to do with paying customers watching.

I also noticed that there was a very small amount of chloroform added to the sandarac varnish recipe. Obviously, chloroform is a restricted substance here but the guy who made my acrylic silver tank told me that he uses chloroform to ‘weld’ the acrylic together… so I may ask if he would be so kind as to drop a few drops of it into my varnish for me.

 

Anyway, so after reading and thinking about this for a little while I decided to say what John Coffer had to say about varnishing and in one of his MythBusters PDF’s I found that he in fact uses these giant ‘hot water’ tanks. Fills them with boiling hot water and then simply sits his plates on top of the hot tank to dry and heat to varnish temperature, varnish, and then sit it back on the tank to cure and dry. This seems to be the answer to my problems as far as heating a large plate evenly. A very hot (but not too hot, I guess it’s not going to get over boiling temperature I think) even surface.

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So I went to a local kitchen supply store and bought these 16×20 inch tin baking trays. I sealed them together with silicone and clamps and then once dried I drilled a couple of holes in 2 corners, one for pouring in the hot water (glued in a little funnel) and one for vent.

Just now I poured in some hot water from the tap to try it, and although the water was not boiling it seems that this large ‘tank’ seems to cool the water inside it rather quickly with the ambient temperature outside (and it is winter here in Tasmania) with the convection of the thin tin trays.

So I thought it might be a good opportunity to try and see if the IEC laboratory heat plate will help in keeping the water inside warm. So far it seems to be doing a good job, I just hope that the silicone holds.

 

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Here is an old rubbish 11×14 plate heating on it as I write this. It is a little slower than I thought, perhaps it would pay to just start with boiling water next time. Will report back on this.

So also doing some brainstorming about the development I thought about a helper tray, which was the obvious solution. The problem I’m having with 11×14’s now is that while letting the bottom of the plate sit in a little ridged edge of wood so that I didn’t have to hold/suspend it fully in my hands free’s up a lot of attention for developing, it was still sometimes the case that the developer vessel would slip off the edge of the plate, spilling developer or missing sections of the plate. I figured with a developer ‘helper’ tray that the plate can sit on and can also act as a guide along the top edge to run the developer vessel across, hopefully it removes the problems and I don’t suffer them with 12×20 plates. However, whether I can maintain a good angle during the pour to ensure the developer flows evenly down the face of the emulsion will be the next step. I just knocked up a quick ‘prototype’ out of wood to see how it works… I played with it, testing running the dev vessel along the top of a plate and it seems to work ok, erganomically it is a little difficult and doing it quickly enough that I can then drop the vessel and pick the plate up off the helper tray to start agitation is another big challenge. I need to do it all in about 1 to 1.5 seconds.

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Hopefully reporting back soon! Looks like my 450mm lens has left Melbourne today so should be here tomorrow or Wednesday… fingers crossed!!!

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