Photography on stone, protecting it...
First of all a big hello from a new member of the APUG website. I've been reading your posts for quite a bit now and decided that has finally come the time to join you in discussing the old fashioned photography.
And now let me present you my problem...
...this year I joined a school of photography near my town and I'm really enjoying every minute I spend there, discovering new things on photography, especially the darkroom part. In fact at the end I want to specialize myself in analog photography.
So, for the ultimate project this school year we decided to join some stone artisans and combine photography and stone together. I'm aware of the procedures how to create and fix a photo from a negative to the stone (using liquid emulsion) and we I and my group also have some back-up plans like using acid etching, sanding or even laser techniques. Of course the last ones will need some deviation from our original plan to put true photography on stone, since these techniques can't display so much tonalities.
The problem we have is how to protect the developed photo on the stone from atmospheric influences, like sun, rain, snow,... As these pieces of stone are going to be benches.
We are aware that all these factors are going to "destroy" our hard work in less than a year (if not even sooner), so we are looking for a coating that we could use to stop this process.
If anyone here has ever dealt with a similar problem, please share your experiences with me (our group). Thank you very much!
Welcome to APUG.
I've coated emulsion on various surfaces including wood, however mainly on painted surfaces (metal) and we always lacquered the resulting image with a clear tri-pack acrylic paint. This was mostly on vehicles, vans/cars and had to stand up to the weather. The major issue is thermal expansion of the stone/emulsion/lacquer relative to each other, indoors the images will last indefinitely, I have some that are over 35 years old.
As a geologist, I will have to say that it depends on the stone!
With a rock with any porosity it might be possible to have the emulsion soak into the stone, a fraction of a millimeter will be enough, which will increase the durability of the result.
Most rocks have a lot more surface permeability than most people think.
Maybe "alternative processes" could come in handy here, a cyanotype mix has much lower viscosity than a gelatin emulsion and will soak in better.
-- Ole Tjugen, Luddite Elitist
Rain is probably your biggest enemy, along with abrasion. You could try something like this: http://www.nanoshell.co.uk/product/stone-waterproofing (I have no experience with this particular material, just googling)
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Depending on the stone, i'd think that a stone sealer may work... Although i'm not sure how the emulsion would react to that. You could always cover it in a thick layer of resin. A popular restaurant in my town uses old doors with a bunch of old photos on them as a bar. And they basically put a 1/2" thick layer of resin on top. You can still see the pictures just fine, the resin is mostly clear, aside from a slight orange tint. This bar has seen thousands of plates, a lot of water, etc. and still looks fine. I don't know how this would work on a stone though...
I would think protecting the images from sunlight (UV) would be particularly important. The weather really will attack just about any project like this. Some kind of clear, UV-filtering coating would be in order.
Several years ago the Oregon state parks people put up informational signs all along the coast describing what people could see from various viewpoints. They were all some type of photo-resist material on stainless steel or aluminum bases. They now are so faded they can't be read. Rain, sun, wind, heat, and cold will fade just about anything, I'm afraid.
I have no experience with what you are looking to do but clear polyester resin as used in boats comes to mind. When I built my darkroom in 1976 I used marine polyester to coat the wooden sink and counter tops. It is still intact and in good condition and has never leaked.
How about images like those on grave stones? I believe they are basically carbon prints (made with ashless gelatin) fired onto ceramic and then placed onto the headstones.
At least with LF landscape, a bad day of photography can still be a good day of exercise.