Pouring plates, big ones.

Ray Rogers · Oct 20, 2009

Photo Engineer said:
Ray;

The clean uncoated plates are warmed in the oven before coating.

They are coated warm and then chilled. When chilled they set up and can then be placed in a cool dark drying rack!

PE

I understand that they are still un coated, but what I am thnking about is spoiling the glass surface...

So after all the effort of cleaning the plates to remove all traces of dust, dirt oils and grease... you just (gently) drop them onto the ktchen oven rack... flat I presume... for a short heating?

Well, if it works it works- but it seems a bit odd to clean something so well and then put them face down in the kitchen oven.

How long do you heat them for?

Ray

totalamateur · Oct 20, 2009

No- really my oven is clean!!

OK, I suppose if you use your oven more often than I do, a nice piece of silpat or possibly one of those dollar store aluminum turkey tins would suffice to lay the glass in when heating.

I turn on my oven to warm, and let it heat to about 150, then throw the plates in for about 5 - 10 minutes. I do not measure the temperature precisely, but more by feel (gloved hands, of course)

Photo Engineer · Oct 20, 2009

So, stack them up and discard the top and bottom plates. The rest are protected from the oven environment except for the heat.

PE

wildbillbugman · Oct 20, 2009

Say, how about a good old record player....

A table-top centrifuge with a rheostat for exact rpm controle would be very effective for spin coating. I bought both the centrifuge and a table top rheostat for future use. Have not tried it yet. I need to figure out how to secure the glass plate while maintaning ballance.
My research on table-top spincoaters indicate that I could buy a brand new Lexus for less $.
Bill

keithwms · Oct 20, 2009

wildbillbugman said:
I need to figure out how to secure the glass plate while maintaning ballance.

How about a circular plate made of 1/8" or 1/4" aluminum or similar, fitted with clips or ridges or a recess to hold the plate. The attachment to the rotary shaft would be via the underlying plate. Thus no attachments to the plate itself are necessary.

Actually I don't think you need variable speed control, you just need reproducible speed. So a record player may be just fine. The thickness of the resulting film could be controlled by time and the viscosity of the fluid.

wildbillbugman · Oct 21, 2009

But the viscosity would have to be very low for record player rpm. The aluminum plate idea is a good one. It would fit right into the lip at the top of the centrifuge.
Bill

Kirk Keyes · Oct 21, 2009

As far as heating plates goes, Denise Ross uses a small food drier heater that is placed into a little plywood drying cabinet that she has in her darkroom. It's about a 1 or so square, and a few feet tall, and the food drier sits in the bottom. She then has shelves (or was it slots that the glass slips into) for the sheets of glass. She put them in and lets them get up to temp before she coats. It's a nice setup and takes just a little space from her darkroom.

Hopefully, Denise will swing by here and correct any errors I made in the description.

Photo Engineer · Oct 21, 2009

I turn my hotplate on low and cover it with about 4 layers of paper towels. I place one 4x5 sheet of glass on at a time and the glass reaches about 100 F. The hotplate has an indicator lamp to tell when the heat is going above a certain value and I can control it easily from the front dial.

This is a high-end hotplate. I don't suggest doing this with a unit with poor indication of overtemp or poor temp control.

PE

Kirk Keyes · Oct 21, 2009

Photo Engineer said:
This is a high-end hotplate. I don't suggest doing this with a unit with poor indication of overtemp or poor temp control.

Yeah, the paper towels might catch fire with a cheap hot plate that doesn't have good heat distribution!

Kirk Keyes · Oct 21, 2009

I have an Infrared Thermometer that I bought at Harbor Freight for about $20. It has a laser pointer to show you where you are aiming it and a digital readout to tell you the temperature of the surface that you are measuring. It might be a handy device for figuring out it your plates are at the right temperature.

dwross · Oct 21, 2009

Kirk Keyes said:
As far as heating plates goes, Denise Ross uses a small food drier heater that is placed into a little plywood drying cabinet that she has in her darkroom. It's about a 1 or so square, and a few feet tall, and the food drier sits in the bottom. She then has shelves (or was it slots that the glass slips into) for the sheets of glass. She put them in and lets them get up to temp before she coats. It's a nice setup and takes just a little space from her darkroom.

Hopefully, Denise will swing by here and correct any errors I made in the description.

You did good, Kirk! And I do have a nice setup, if I say so myself . I live in a climate that's decidedly chilly a good deal of the time. My little warming box just takes that chill off my plates. I don't think elaborate (i.e. expensive) heating devices are necessary for your glass plates. In truth, the real variable creeps in as you transfer your plates to the coating area. It's hard to even guess how many degrees are lost in the process. I go so far as to warm up my darkroom to about 72F before I start coating, and that seems to be enough to do the trick.

Far more important is keeping the emulsion temperature within a narrow range, and making each batch of emulsion small enough that you can get the coating done quickly. Emulsion continues to ripen as it sits. Too long in the holding bath and it can even start to fog. That's also the main problem with planning on re-using emulsion from a previous session. Even if you don't add hardener (and I don't to my negative emulsions), the re-heating process will significantly change the characteristic curve of finished plates.

d

Ray Rogers · Oct 21, 2009

Qs

Kirk Keyes said:
... a small food drier heater....

What is a Food Drier Heater?
Farm equipment or something like that?
What foods need dryers?

What is Harbor Freight and what sort of products do they sell?

Ray

dwross · Oct 21, 2009

I figure this link is a natural to your location, Ray!

Dead Link Removed

Read about the convection style on the second page, and let Google do your walking from there.
d

willrea · Oct 21, 2009

Ray Rogers said:
... a small food drier heater....

Click to expand...

What is a Food Drier Heater?

Maybe something to dehydrate food?

Harbor Freight is a hardware store.

Kirk Keyes · Oct 22, 2009

Ray Rogers said:
What is Harbor Freight and what sort of products do they sell?

Harbor Freight sells mostly imported tools. From what I saw, it's not near the quality of what you can pick up at Sears.

Anyway, the IR temp meter was inexpensive and works.

Kirk Keyes · Oct 22, 2009

willrea said:
Maybe something to dehydrate food?

Yes, a food dehydrator. But Denise is using just the heater and putting that into a cabinet.

Ray Rogers · Oct 22, 2009

willrea said:
Maybe something to dehydrate food?

Harbor Freight is a hardware store.

OIC.

I totally forgot about dried herbs, dried tomatoes, friut leathers, figs, apricots and so on. The pound or so of herb I might wish to dry just air dries naturally.

Ray

wildbillbugman · Oct 22, 2009

In truth, the real variable creeps in as you transfer your plates to the coating area. It's hard to even guess how many degrees are lost in the process.

......................................................................................................

Denise,
Have you thought about heating your coating frame? I use a coating frame similar to your`s. But I use oinly one glass frame for multiple plates. As I recall,you set up a frame for each plate. A small amount of heat, like a heating pad on low, under the frame would keep the heating frame at constant temperature. You could keep the plates in the dehydrater. Then transfer to the heated frame.
This is pure conjection on my part. I use one frame, unheated, for multiple coatings. I do not heat the plates
But the truth is: No matter what the coating method, I am a putz, no matter what the method.
Bill

dwross · Oct 22, 2009

Hi Bill,

Before I coat my plates, before even I start melting the noodles, I arrange all the plates for coating. I set each plate on a piece of silicon matting that is in turn set on a piece of rigid acrylic. I surround each plate with four strips of glass to allow the emulsion well and coating rod to ride quickly and evenly over the whole of the plate. The strips stay in place until the plate is dry. They keep the emulsion from running all over the place before it sets up. I don't preheat the glass. I coat so quickly (2-3 seconds/plate) that room temperature glass is actually an advantage. By the time I have washed and dried the well and puddle pusher for the next plate coating, the plate I just coated has set up enough to carefully move out of the way for complete drying on a level shelf.

And you are not a putz. Far from it. You do remarkably well considering what your poor hands have been through. I keep trying to think of a way to make it easier for you. We'll come up with something.
d

studiocarter · Oct 23, 2009

A water bourn clear coating might work.
Bill

Just got back and was very surprised to see so many posts??!!
Bill, from page 2: I tried that, ie. water based polyurethane sub coated glass, and the ENTIRE image lifted off into my hands. I'd dried the developed subbed plate in the oven because it had bubbled and lifted off the glass in room humidity. It is very dry in the oven because of the pilot light; it went flat; humidity in the room caused it to totally lift off even after it had gotten flat. It was flat long enough to scan into the computer.
Lifted off free emulsion pictures is something to keep in mind for very expirmental works. The emulsion, free from the glass, is very tough like leather and will not tear easily. It could be glued onto things.

wildbillbugman · Oct 24, 2009

Studiocarter,
You may have misunderstood. I was not sugesting water based subing. I was sugesting water based EDGING, specificly for collodion. The idea is to have the collodion repelled by the coating at the edges only, not to coat the entire plate with water based subbing.
I dip the edges of each cleaned plate(wearing powder-free gloves) into hot wax.
When I pour my emulsion, the emulsion is repelled from the edges but adheres very well to the clean glass. Lack of adhesion of emulsion to glass is NEVER one of my problems.
Bill

wildbillbugman · Oct 24, 2009

I keep trying to think of a way to make it easier for you. We'll come up with something.
d[/QUOTE]

Denise,
Think of a way to get me intrested in kniting or basket weaving, or something that dose not involve substances in a fluid state.
Every one else,
My recomendation for a waterbourne coating was specificly for Collodion. NOT for silver gelatin emulsions!
Bill

removed account4 · Oct 24, 2009

hi bill

you don't sub your dry plates ?
maybe i am misreading what you wrote, but you get your emulsion to
anchor onto the smooth glass surface without an intermediary layer for the emulsion to grab onto ?
i've never been that lucky ...

i've coated plates since the 1980s and in the beginning my biggest stumbling block was not knowing how to get the emulsion to stick the glass.
i had no problem getting the glass very very clean, but no matter what i did,
emulsion lifting off of the plate was always an issue.

in the end i was able to control the "lift" so i could make it happen when i
wanted it to and get a hand poured version of a polaroid emulsion transfer but on glass instead of on paper ...

Photo Engineer · Oct 24, 2009

I don't sub glass plates and AFAIK, many brands of commercial glass plates were not subbed.

The key, I am told, is the chrome alum hardener.

PE

removed account4 · Oct 24, 2009

thanks ron!

john

Pouring plates, big ones.

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