purpose of sheet mirror?

[smeylan]

I got a fairly complete, serious set of darkroom equipment off of Craigslist about 10 years ago... over time I've figured out what basically everything is, but I'm still vexed by a set of ~11x14 sheet mirrors (~1/16" thick). They have protective paper envelopes but no labels or product numbers. What would one use this for in the darkroom?

[Michael R]

Offhand all I can think of would be for ferrotyping prints, although 1/16” seems awfully thin/delicate.

[Doremus Scudder]

Ferrotyping plates. Used to give fiber-base paper a mirror-like gloss finish instead of the more textured air-dried finish.

Doremus

[smeylan]

Thanks everyone, they are definitely ferrotyping plates. Scratched and dented so I'm afraid I won't be able to experiment with them, but good to solve that riddle.

I guess this also explains why the collection of stuff also had an old electric print dryer.

I found this YouTube video on ferrotyping plates good for reference / how they are used: https://www.youtube.com/watch?v=P5NMY4r2Obc

[LabRat]

Glass works very well, but with the danger of cuts and breakage... I bought a box of framing lites from the wholesale framer and used it on a project where gloss was needed after multiple toning affected the surface of prints and needed treatment...

Skimmed the video, but saw presenter didn't have much practical experience with the process... This is an exacting process with much care needed... Biggest omission was the need for plates to be flat stable, chemically clean, and the fact that prints are not to be "stripped" off plates or it causes damage to surface... Prints need to dry evenly throughout process and to "fall off" when ready... (This is after prints have "glued" themselves to plates due to gelatin sticking...)

There were some solutions that didn't allow prints to stick, but gone now are the products... Old books had a recipe for a solution that involved going to a slaughterhouse to get an ox gall bladder and squeezing the extremely vile smelling solution out of it as an ingredient...

Other release treatments involve cooking spray oils, but this leaves an oily residue that looks like Newton's rings...

The last commercial product was Pakosol made for drum dryers, but probably gone for good...

The best perfect gloss surface is just using good 'ole RC...

BEWARE OF INFORMATION!!!

Steve K

[Tin Can]

Good to know

I almost bought new ferro plates some years ago

Then I got a huge nd heavy ARKAY ferrotype dryer, that had a good cloth and perfect drum for free

6 years later I gave it away and never used it

I think they sold new somewhere north of $3K

I have tempered glass

[Michael Graves]

... Old books had a recipe for a solution that involved going to a slaughterhouse to get an ox gall bladder and squeezing the extremely vile smelling solution out of it as an ingredient...Other release treatments involve cooking spray oils, but this leaves an oily residue that looks like Newton's rings...

Bet that improved the archival qualities of the paper immensely!

[Paul Ron]

hahahaha ox gall bladder? ill go grab my neighbors ox.

the solution kodak made was glycerine based.

here is an interesting thread on the subject...

https://www.photrio.com/forum/threads/ferrotyping.142025/

[mdarnton]

Referring to the thread, basically the glycerin is for flattening, wax is against adhesion to the plate. The glycerin *might* have helped with adhesion, but basically what it does is make the paper and emulsion more hydroscopic, which means it stays relatively soft and flexible by always keeping the print a bit damp. If one is worried about that archival thing, maybe that's not so good. If you're going to wax, some experimentation might be required; I imagine the surface might be affected by the wrong wax. . . but if it doesn't work it's easy enough to get off.

[Paul Ron]

archival? hahaha ive got ferrotyped fb prints from the 60s that are still in pristine condition. i doubt your priceless museum quality prints will degrade in your lifetime.

[LabRat]

hahahaha ox gall bladder? ill go grab my neighbors ox.


Why, it's biblical law not to covet thy neighbors ox or ass (Google "10 commandments")...

And is your neighbor's ox alive in the pen when you enter with a knife to remove said gall bladder!?!!! Beware if the ox is in heat and the hunter becomes the hunted??? ;-)

Steve K

[Paul Ron]

hahahahahahaha:o