Large Warm Darkroom Trays

[Carnie Bob]

Hi There.

I am looking for a solution for my Gum Printing. I require a 30 x 40 inch darkroom tray that can keep the water warm at all times . I have kind of searched food warming stainless steel but nothing is becoming obvious to me
Any help would be appreciated.

Bob

 

[MattKing]

One of my all-time favourite APUG/Photrio threads: https://www.photrio.com/forum/threads/sue-weeee.25459/
I believe that Murray has updated information now - but still .......

 

[Carnie Bob]

One of my all-time favourite APUG/Photrio threads: https://www.photrio.com/forum/threads/sue-weeee.25459/
I believe that Murray has updated information now - but still .......

I was actually on this original thread and I do have a pig warmer , problem is it does not get hot enough to transfer through my plastic trays to heat the water, I am thinking of a stainless steel tray which would conduct the heat better or figure away to make the unit go hotter.

 

[koraks]

How about put a big tub of water underneath your sink with a heavy-duty heating element in it on a thermostat. Then run a pump and a drain hose to your tray so there's a constant stream of water of the desired temperature going through the tray.

The main drawback for gum printing would be the motion of the water, I imagine. To handle that, you could use a tray-within-a-tray setup (a bain marie in fact) with the other tray having the water circulating around the inner tray.

 

[bluechromis]

This has probably been thought of, but there are the electric food warmers that get pretty hot. So the OP's question is really about a heat-resistant tray that could sit on a heater, not about the heat source per se?

 

[bluechromis]

How about put a big tub of water underneath your sink with a heavy-duty heating element in it on a thermostat. Then run a pump and a drain hose to your tray so there's a constant stream of water of the desired temperature going through the tray.

The main drawback for gum printing would be the motion of the water, I imagine. To handle that, you could use a tray-within-a-tray setup (a bain marie in fact) with the other tray having the water circulating around the inner tray.

Going with the tray in a water bath idea, why not use an immersion heater(s) in the water bath tray, which would both heat and circulate the water?

 

[mshchem]

Doran / Premier made a 600W (IIRC) immersion heater for the water bath of their tube processor.

Maybe buy an Arkay SS sink and slap a pig warmer underneath

 

[mshchem]

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This is overkill, lots of used circulation bathes on Ebay, 200 bucks.

 

[randyB]

What temp do you need the water to be?

 

[Kino]

Cheap Sous Vide cooker. A $50 one on Amazon has a temp range of 25-92.5 Degree Celsius ( 77.0-198.5 Degree F ).

I would think that would cover most needs...

 

[mshchem]

My father was a gardener, he had a small greenhouse. Dad used some sort of warmer (resistance heater) in a big tray of sand to help to accelerate the germination of seeds. Maybe a sand bath to set the tray in with a heat tape and a controller

 

[Mal Paso]

30x40 trays are going to need a few thousand watts to maintain temperature. You can insulate the underside but that's a lot of surface area bleeding heat.

 

[markbau]

Here in Australia they sell heating mats to keep kegs of beer at a pre set temp while they ferment. Mine works like a treat but I only use max 16x20 trays now. There are also mats for keeping seedlings at a pre set temp that I've seen at a friends place that would do the trick but my beer mats work perfectly so I didn't investigate further. You might need two for a tray as big as yours. A fish tank heater/s may work too if you have a larger tray for a water bath.

 

[koraks]

Cheap Sous Vide cooker.

They're like...1kW max? Sounds a little small for such a big tray. I use a sous vide (800W) sometimes, too; it does OK, but I'd hesitate to recommend it to Bob for this specific application.

I only use max 16x20 trays now

Keep in mind that 30x40 is about four times as large.
Let's say the heating element on the sous vide is 1kW, the tray has about 4" of water sitting in it and you want to warm it from 18C to 30C. This will take (without any losses) over an hour. Two sticks should cut it down to half an hour.
You could start by boiling water in a kettle, use that to raise the initial temperature and then use a single sous vide to keep the water at temperature.

Might work, in a pinch.

 

[Don_ih]

The surest solution would be a heating element and a temperature probe - like in a Jobo.

The heating pads (mentioned by @markbau ) are very low wattage but, given the size of some of them, you could put 4 under a huge tray like that and they would likely be able to maintain the temperature of the water in the tray while you used it. I doubt they'd be able to raise the temperature very quickly., so you'd want to start with the water the correct temperature. If you were leaving the tray permanently filled and always wanted it at the proper temperature, those pads seem to be designed to do exactly that.

 

[Carnie Bob]

Doran / Premier made a 600W (IIRC) immersion heater for the water bath of their tube processor.

Maybe buy an Arkay SS sink and slap a pig warmer underneath

I am at this stage right now , thinking of this option.

 

[Carnie Bob]

The surest solution would be a heating element and a temperature probe - like in a Jobo.

The heating pads (mentioned by @markbau ) are very low wattage but, given the size of some of them, you could put 4 under a huge tray like that and they would likely be able to maintain the temperature of the water in the tray while you used it. I doubt they'd be able to raise the temperature very quickly., so you'd want to start with the water the correct temperature. If you were leaving the tray permanently filled and always wanted it at the proper temperature, those pads seem to be designed to do exactly that.

The pig warmer was really big so it would fit well under the stainless steel tray, it did not work so well with my thick plastic trays, good idea about preheating the water and the tray as well.

 

[Carnie Bob]

Going with the tray in a water bath idea, why not use an immersion heater(s) in the water bath tray, which would both heat and circulate the water?

The tray is to hold the first water bath for gum which captures all the dichromate, like Christina Anderson this bath never needs to be changed so I could keep it going for years and when wanting to dump , sump pump the neutralized water and let it sludge out before going to city waste management. I have larger 34 x 44 trays that could be flipped on top to avoid evaporation when not in use. I am worried that the chemicals may be harmful to the immersion heaters , and I have only seen the kitchen type which would not be practical for a flat stainless steel tray.

 

[Carnie Bob]

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This is overkill, lots of used circulation bathes on Ebay, 200 bucks.

I would be recycling dirty pigmented water ,, after a few sessions the water is black, and I plan to keep the bath like this for over a year. just reheat the water each time.

 

[Carnie Bob]

What temp do you need the water to be?

About 85- 100 degree F is the best for my needs, the warmer water has a good effect on the gum when it is first immersed in the develop/washout stage

 

[Carnie Bob]

Cheap Sous Vide cooker. A $50 one on Amazon has a temp range of 25-92.5 Degree Celsius ( 77.0-198.5 Degree F ).

I would think that would cover most needs...

they are mostly vertical, I. use one for my stainless steel dip dunk line but would not be practical for 2 inch depth tray

 

[Carnie Bob]

Here in Australia they sell heating mats to keep kegs of beer at a pre set temp while they ferment. Mine works like a treat but I only use max 16x20 trays now. There are also mats for keeping seedlings at a pre set temp that I've seen at a friends place that would do the trick but my beer mats work perfectly so I didn't investigate further. You might need two for a tray as big as yours. A fish tank heater/s may work too if you have a larger tray for a water bath.

did not think about fish tank heaters- thanks for the lead

 

[Kino]

they are mostly vertical, I. use one for my stainless steel dip dunk line but would not be practical for 2 inch depth tray

Well, I agree. The 2 inch depth information would have been helpful up-front.

 

[Carnie Bob]

Well, I agree. The 2 inch depth information would have been helpful up-front.

How many darkroom trays have you seen that are over 3 inches in depth, just sayin

 

[Kino]

There are these seeding pads on Amazon that are 10 x 20.75 inches, like Don_H suggests, that are fairly inexpensive at $15 each.

Sorry, Amazon links don't work here but search by this title: "

VIVOSUN Durable Waterproof Seedling Heat Mat 10" x 20.75" UL & MET-Certified Warm Hydroponic Heating Pad for Germination, Indoor Gardening, Greenhouse​

Temp: 68-86℉(20-30℃)

The version with a digital thermostat is about double the cost.