PDA

View Full Version : Dry plates with acryllic or polycarbonate base



Falkenberg
05-14-2008, 11:38 AM
Has anyone tried the combination of liquid emulsion and acryllic plates or polycarbonate plates. There are several plastics on the market that are transparant and cheaper than glass. they are also easier to cut. But can they work as a base for dry plates ?

Falkenberg
05-17-2008, 02:55 AM
I have had contact with a danish company that sells plates in many different materials and they will try to find out wich will work.

Kirk Keyes
05-17-2008, 11:56 AM
I don't see a reason it would not work. The emulsion may stick to the plastic a little better even, with all the static that plastics generate perhaps that would help.

Murray@uptowngallery
05-17-2008, 12:23 PM
I know you are into ULF, and if cost is an issue, I assume you are implying somethign larger than 4x5?

For anything larger than, arbitrarily, 4x5, I'd be concerned about flatness, rigidity, etc. It flexes pretty easily and while it may have been due to the protective paper (although it is on both sides), I have seen acrylic that did not sit flat.

I previously had concerns about using it for viewing in view cameras...same physical issues for using it as plates.

An experiment with a small piece won't cost much & may work just fine!

Murray@uptowngallery
05-17-2008, 12:28 PM
I find acrylic & polycarbonate in 1/8" to be much more costly than glass...must have something to do with petroleum prices:mad:

Ian Grant
05-17-2008, 12:37 PM
The secret is going to be hardening the emulsion, so there's less chance of it frilling at the edges and beginning to lift off. That's assuming you can coat it evenly in the first place. The surfaces of acrylic and polycarbonate are quite different to glass.

On a small scale I'd use an airbrush to spray a very fine gelatin subbing layer onto the surface first, with a small amount of Chrome Alum added to it. I experimented with applying emulsions to a very wide variety of surfaces just over 30 years ago. Later on a commercial scale where necessary we sealed the surface with an acrylic lacquer, then used 600 grit wet & dry to prepare the surface before applying the emulsion. I wouldn't advocate that for negatives but it works extremely well for prints,

Ian

eclarke
05-17-2008, 12:43 PM
Check for clear, rigid polyester sheet. Some film base is polyester..Evan Clarke

jnanian
05-17-2008, 12:47 PM
i have a few plates i coated with liquid light a while back.
they are plexiglass, and i used polyurethane as a subb.
they LOOk fine, but i haven' t exposed+souped them yet.

i will report back when i do ..

--john

richard ide
05-17-2008, 01:54 PM
I would recommend that you use a plastic sheet which is cast rather than extruded. Cast acrylic is readily available. I think most other plastic sheeting is extruded. Extrusions will change dimension over time due to creep. I wonder what sort of pricing you could get from a glass company if you stated your purpose and maybe bought a dozen sheets at a time. If you specify "select" quality you should get pieces with no discernable flaws. Cutting glass is very easy and use sandpaper to touch up the edges.

dwross
05-27-2008, 12:35 PM
This thread got me interested in the different possible coating substrates. Actually, I like glass just fine. It's cheap and easy to handle and reusable. I never have managed to reuse a piece of acrylic when it's been required for hanging in a show or gallery so I don't think it would go well for plates either. And, at least around here, it's darned expensive.

After glass, the Melenex subbed film that the Formulary sells works great. I've been working through a couple of packages. The surfaces are scratched from the cutting technique they were using, so I won't be able to use the negatives for exhibition, but it works just fine for experimenting. I can only hope they get the cutting problem solved soon. That's the reason the Melenex is listed as 'out of stock'. I can't imagine how busy they are getting ready for the workshop season, but maybe if a couple of people besides me nagged them about it...:)

Back to the acrylic, though. I set the Melenex on thick sheets of plexi for support during coating. The emulsion that spills over seems to stick just fine to the acrylic.

One more item: In what is proof positive that the greatest theoretical idea can be oh so very dumb - don't bother trying to coat Pictorico OHP. It seemed like a natural when it came to me in the middle of the night. Nope. Doesn't work. Really doesn't work.

Happy cooking,
d

Kirk Keyes
05-27-2008, 03:12 PM
Denise - what problems did the Pictorico have? Not sticking I assume, but can you give a more indepth answer.

dwross
05-27-2008, 04:18 PM
Denise - what problems did the Pictorico have? Not sticking I assume, but can you give a more indepth answer.

Double bubble, toil and trouble, Kirk. The subbing grabbed the emulsion well so that it wouldn't slide smoothly and the emulsion clumped and gooped (a technical emulsion term, and a dark secret until now). But your assumption is spot on. The clumps and goops aren't going anywhere unless they would lift away along with the subbing in the developer. Mine never got that far.

Steve Smith
05-27-2008, 04:24 PM
It is possible to buy polycarbonate and polyester with coatings or surface treatment to accept screen printed layers. I suspect that some of these treatments may also assist in bonding emulsion. It would require a bit of testing though.

In the US, the main manufacturers are General Electric (for Lexan polycarbonate) and Dupont (for Mylar polyester). It is also possible to get a polyester/polycarbonate blend from Bayer.


Steve.

Kirk Keyes
05-27-2008, 04:48 PM
The subbing grabbed the emulsion well so that it wouldn't slide smoothly and the emulsion clumped and gooped (a technical emulsion term, and a dark secret until now).

What about prewetting the OTP sheet, perhaps with wetting agent, and then coating?

Kirk Keyes
05-27-2008, 04:50 PM
Sounds like an cationic/anionic thing going on...

I understand if you have cationic emulsified asphalt that it will do the same thing you describe when you put it down on an anionic emulsified roadway, and vice versa.

dwross
05-27-2008, 06:29 PM
Sounds like an cationic/anionic thing going on...

I understand if you have cationic emulsified asphalt that it will do the same thing you describe when you put it down on an anionic emulsified roadway, and vice versa.

Sounds like double bubble, toil and trouble to me.

Steve: Thanks for the brand name suggestions. I've written them down and stuck the note on my bulletin board for future reference. If I had to guess, I'd think that surfaces prepared for screen printing would have similar characteristics to OHP, which is made for inkjet printers, but any subtle differences just might make all the difference. As you say, testing will be required.

Right now, I'm holding on to the hope that Photographers' Formulary will start selling their Melenex again. If they don't or on some eventual day when it runs out, it will be time to go on a serious quest for available alternatives, or of course, a good recipe.

d

Photo Engineer
05-27-2008, 06:46 PM
The OTP and indeed all digital print materials have a large load of mordant in a vehicle that absorbs a lot of water quickly. It therefore clumps and goops. :D

I have coated successfully on such materials, but the mordant reacts with 'something' and forms a dark brown stain at the end of the processing regardless of fix and wash times. Not good at all.

PE

Aurum
06-25-2008, 04:35 PM
Sounds like an cationic/anionic thing going on...

I understand if you have cationic emulsified asphalt that it will do the same thing you describe when you put it down on an anionic emulsified roadway, and vice versa.

I know the cationic/anionic thing well. :o
I've worked in a factory where we made a range of bodylotions with anionic chemistry, and one solitary one with cationic (It was based on hair conditioner chemistry).

Try to pump one into a filling machine to displace the other (Known as bulk on bulk) when changing products. Not good.....
Think greasy scrambled eggs, rolled in cooking oil and cottage cheese.
The line setter who thought he'd save a hour or so on washdown ended up having the joy of stipping and cleaning the machine by hand.
He was on his own for that

Want to try this at home.. Mix a small quantity of a lotion type hair conditioner with a cheap body lotion. Yum

Kirk Keyes
06-25-2008, 10:38 PM
Pretty crazy, huh?!

Photo Engineer
06-26-2008, 10:48 AM
Well, you do not mix anionic and cationic organics that have high molecular weight. Otherwise, you get the result as described.

Just ordinary chemistry.

PE