Old drymount press

[Stefan Findel]

I have an old drymount press (Seal Commercial 200), on which the temperature drops off from 220F in the center to 190F halfway (!) towards the corners. Is this a problem for mounting fiberbased BW prints? Is the temperature on a new press completely even all across? Thank you.

 

[RJS]

As is often said about lemons . . . suck it and see. . . Nothing is ever even or without variation. Sounds fine - just try it out after reading how to mount!

 

[Paul]

I suspect that both of those temperatures are sufficient to activate the adhesive. Don't forget to use release tissue.

 

[JBrunner]

How are you measuring this? The press needs to be heated closed, and must be fully up to temp, as in has sat at temp until the pilot has gone off.

 

[mrportr8]

It depends on what drymount tissue/adhesive you are using and the activation temperature. Most have a range for example: 175 F - 210 F. As long as you are within that range results will be fine. Be careful if your press spikes above 220 F as you may risk damaging the emulsion, especially any inkjet prints. Most Lambda and LightJet prints cannot tolerate heat above 165 F for prolonged periods. RC papers should be kept closer to 190 F or below. Keep dwell time (time in the press) to a minimum as well. Usually 3-4 minutes maximum after which you risk transferring the adhesive off the carrier tissue and into the substrate or paper (if you are using FB B&W paper).

 

[nickandre]

I found that when I dry mounted that a temperature of 150 for 20 seconds was fine. I've heard that higher temperatures are worse. I've gotten some bad marble effect on the gloss paper.

 

[Stefan Findel]

Thank you for all your input. This is the first time I tested this press. I let it warm up for over 30 minutes (closed) and then put 5 measuring sticks in the press and left them for 90 seconds. I only do BW fiber based prints, currently using Bienfang colormount, which requires 190F for these prints. From past experience I know I would have adhesion problems if I go less than 190. What worries me is that the 220F may be too much, but that that may not be evident until some time later. ? (Maybe I am too fussy...)

 

[JBrunner]

Thank you for all your input. This is the first time I tested this press. I let it warm up for over 30 minutes (closed) and then put 5 measuring sticks in the press and left them for 90 seconds. I only do BW fiber based prints, currently using Bienfang colormount, which requires 190F for these prints. From past experience I know I would have adhesion problems if I go less than 190. What worries me is that the 220F may be too much, but that that may not be evident until some time later. ? (Maybe I am too fussy...)

That is very odd. I don't believe the element in the press covers the whole area and the press is kept to an even heat through convection. Perhaps there are two elements and the outer one isn't functioning. By that reasoning the inner would be doing double duty to trip the thermostat, and your readings are the result. Or perhaps they are all like this, and you are the first to notice? Is the felt in place? Maybe sandwiching between two pieces of mat board will help to even out the heat.

If you could find access to another, you could repeat your experiment and find out if yours is really malfunctioning.

 

[Stefan Findel]

... I don't believe the element in the press covers the whole area and the press is kept to an even heat through convection. Perhaps there are two elements and the outer one isn't functioning. By that reasoning the inner would be doing double duty to trip the thermostat, and your readings are the result. Or perhaps they are all like this, and you are the first to notice? Is the felt in place? Maybe sandwiching between two pieces of mat board will help to even out the heat...

Jason,
actually, ONE corner almost gets up to 220. And yes, the felt is there, and I always sandwich between 2 matboards. One thing I did not consider that important though: I did not apply full pressure, just medium pressure, i.e. the handle was at 35 instead of 45 degrees before closing. Maybe that is why, but I have my doubts. I have to first get more teststrips, before I can repeat the test with full pressure. I will post the result.
Stefan

 

[rexp]

Hmmm, I am surprised you are seeing that large of a variation. 10 or 15 degrees F maybe, but not 30. What are these teststrips you are using? When I checked my Seal press I first used one of those cheap electronic oven thermometers with a three foot long lead. It allowed me to move it around without having to wonder about variability in the measuring instrument. I wasn't trying for 1 degree accuracy, just checking uniformity. I did later check using a calibrated electronic thermometer, and was pleasantly surprised how well the cheap meat thermometer worked.

Temperature can be frustratingly difficult to measure accurately, and knowing your measurement methods are accurate is where you should start. Put some of these "teststrips" side by side (or on top of each other if possible) & see if they measure the same temperature.

 

[Stefan Findel]

rexp,
I used indicators from reatec.ch , which I had bought in Germany.
Stefan

 

[rexp]

Stefan; I checked out the website & understand what you were using. One thing to keep in mind is that the temperature can fluctuate wildly during the warm-up phase. Typically there will be an area or two which overshoots considerably before the rest of the aluminum plate comes to temperature. If these strips are attached when the unit is cold, you will be seeing the maximum temperature that spot reached, not the "stabilized" temperature.

Having said that - your post indicates that you let it warm up prior to adding the sticks, so I wouldn't expect that to be the cause of the temperature variation you are seeing. Reatec claims 1% accuracy, so I wouldn't expect the variation you are seeing is due to the measurement instrument either (the sticks).

I'm stumped... Go to the dollar store and buy a candy thermometer or meat thermometer with a long pointy end. Keeping at least 1/2 of the probe clamped, move it around to see if it can detect the temperature variation you are seeing. It doesn't matter if the cheap probe is accurate, only repeatable.

good luck,
RexP

 

[mrportr8]

The temperature variation is still within the activation range of the adhesive. Sandwiching between two boards is over kill though as the top board acts as "insulation" and thus the adhesive takes longer to wet out. I would suggest using a release paper/film or foam blanket instead. Don't bother worrying about a 10 degree temp variation as that is quite normal for that type of press. If you want closer tolerance then look into getting the Hot Press brand glass top press. The glass top has a special coating and thus the entire glass is the heat element and is not reliant on a wire element for heat. I have two, a 35"x47" and 44"x66" and they work flawlessly for the 10 years I've had them. I heard through the grapevine they are coming out with a smaller 20"x24" model soon. A big advantage is that if you use a clear silicone release film, you can see the print during the entire process. You can monitor the print and if you see a corner folding over or hair or dust you overlooked you can stop the process and save a print from destruction.
Fiber based B&W prints (silver halide) papers can handle the heat without any worries. And although most adhesives give a range of temperatures, the low end is usually at least 5 degrees lower than the published spec. This way they have some breathing room for sloppy tolerances on cheap thermostats installed on some machines, and for normal variations in temp on heated platen presses such as yours.

 

[Charlie Zinn]

Hi all, I recently purchased a similar model to the Seal Commercial 200. I got the Seal Masterpiece 350. It has been refurbished once and the wiring in the electrical panel has been replaced with an external Honey Well thermostat. I wonder if the anyone on the forum has a photo of the original electrical box or could lend me some of their experience. I don't understand how the heat element in the original configuration work with the platen?

 

[Arthurwg]

My advice: Try to find a new thermostat as a replacement. They are few and far between but you will probably need one, if not now then eventually.

 

[Mal Paso]

A thermocouple based thermometer will be more economical than strips. I use a $45 electrical multimeter that came with a K thermocouple that is smaller than a grain of rice on small high temp wires. It will reach any part of the platen while closed.

 

[RalphLambrecht]

Jason,
actually, ONE corner almost gets up to 220. And yes, the felt is there, and I always sandwich between 2 matboards. One thing I did not consider that important though: I did not apply full pressure, just medium pressure, i.e. the handle was at 35 instead of 45 degrees before closing. Maybe that is why, but I have my doubts. I have to first get more teststrips, before I can repeat the test with full pressure. I will post the result.
Stefan

You could use an infrared thermometer butthen, You need to pen thepress to measure.

 

[Mal Paso]

Infrared Thermometers don"t read shiny, metallic surfaces well. Google " thermocouple thermometer", there's a bunch for around $30.