Coating a finished cyanotype

[Bob K.]

Does anyone coat their finished cyanotypes? Is it archival?

I know Loris Medici mentions Hydrocote Polyshield Clear Gloss polyurethane in another post. I was wondering what else is being used (if anything), and what are the results.

thank you,
bob k.

[doughowk]

I've used Agfa Sistan on some alt process prints including cyanotypes. Guess I'll have to wait to see if archival ;-), but doesn't seem to change print appearance.

[nworth]

The same materials painters use would seem logical, since cyanotype is a painters' pigment. A thin coat of clear Krylon is a favorite of many people. I doubt if it would have much affect on permanence, however. Air can still reach the image through the back of the paper, and light can reach it from the front, although UV may be somewhat attenuated. Coatings will protect against mild mechanical damage. Cyanotypes seem to be a bit funny about permanence. Some fade quickly, but I have seen at least one (at the San Francisco Museum of the Legion of Honor) that was over 100 years old and looked absolutely new. (AFIK, it was not coated in any way.)

[David William White]

...Cyanotypes seem to be a bit funny about permanence. Some fade quickly, ...

Paper pH is a big factor. Buffered (aka 'acid free') paper cyanotypes fade. Don't know about protective supercoating.

[bowzart]

According to the venerable Photographic Facts and Formulas by Wall and Jordan, Cyanotype is permanent but can fade in strong light. If faded, it can be restored by keeping it in the dark for awhile. (This is from memory; my book is at home, and I'm not, and I have never tried this; never needed to).

I make mine on Arches 88 or BFK unsized, so the image is embedded in the fibers of the paper. I wouldn't dream of coating that beautiful paper. The only trouble I've had in about 35 years is that if I didn't get it washed completely (difficult, like washing blotters) the coated area will discolor at the edges.

[DrPablo]

I treat mine in either tea or dilute vinegar to acidify the paper. That increases permanence.

[Bob K.]

Thank you everyone for the replies, but I need to clarify what I'm looking for in my prints. I know that cyanotypes are archival by themselves. I'm looking to coat them for a different look (gloss, semi-gloss, etc). I'm looking for suggestions on coatings that will work but not effect the archival properties of cyanotypes, but give a different look to the finished print.

bob k.

[bowzart]

Acrylic medium might be something to try. It comes in matte and gloss. Get it where they sell artist's materials. Whether it is more congenial to endurance than Elmer's Glue, I don't know. I always suspect them of repackaging cheaper materials, relabling, and multiplying the price.