First tri-color gum print

I am not sure about it. It takes a long time to get to here and it just must be better than this. Maybe another layer of yellow.

I used .2g/.3g/.6g per 4ml for C/M/Y respectively hoping to get the yellow and magenta to match the strong cyan.

First (semi) successful gum print

There are definitely more failures than successes so far. There are so many variables to this process that it is extremely important to be measured in what you have done. This was printed with Lamp Black (1.5g pigment/10ml gum arabic) and exposed for 1:30 minutes in bright sun. The highlights did not clear even after 30 minutes soaking in tepid water and needed to be aggressively sprayed to clear.

I am happy with the result but it is far from what can be called skill and still quite lucky.

I have just set up an Arista UV light source and can now be precise in the exposure.

Cyanotype Gelatin sized mulberry paper

The gelatin did a great job on sizing this paper. This paper was unusable (way too absorbent) as a base for emulsion without sizing. The cyanotype emulsion did not clear completely from the sized paper though, leaving a yellow color in the highlights. It was unexpected but not entirely undesirable.

Preparing Gum Arabic

I am using Gum Arabic powder for my gum prints.

This variable has got me stumped.

I have read ratios (g/ml of powder/water) from 16 / 100 ("28 grams gum arabic powder to 175ml of water") to 30 / 100 ("300g of gum arabic to 1000ml of water)

I also know that the commercial grade gum arabic in liquid form is 14 Baume.

I have made 10 prints at 16 / 100. The development stage is interesting. After 30 minutes of soak (2 refreshes of water) in tepid water the highlights have not cleared. But, with a directed stream of water, they loosen and clear quite quickly.

I am not sure why.

I also found this.

"SG (specific gravity)=145/(145-Bè)
If you substitute 14 for Bè then what you are looking for is a solution with a specific gravity of 1.106"

Since the Gum Arabic powder does little to the volume, the weight of 100ml (+the volume of gem arabic powder) should be110.6g. It seems to me that a little more than 10.6g of powder should do the trick.

Hmmmm.

Glass Cyanotype

I have been wanting to do this for a long time, but it seemed like a very difficult technique. In fact, it was quite easy!

The general idea is to coat glass with the same photographic emulsion used to make cyanotypes on paper. The problem to be overcome is that the emulsion has nothing to adhere to and would just run off the glass. The common solution is to use Gelatin as a size.

The gelatin was prepared by soaking 2 packets in 500ml of water for 15 minutes. It was then heated to 140-160 degrees Fahrenheit for 2 minutes. This was then mixed 1:1 with the standard cyanotype emulsion. I used 10ml of emulsion and 10ml of gelatin. This is poured onto a VERY carefully and completely cleaned glass plate. The emulsion is rolled around until the plate is coated. Amazingly, with careful tilting, the liquid does not roll over the sides. The excess liquid is poured off the corner of the plate back into the pot or into a paper towel. The plate is then set to dry. I have seen this process done under safelights, but as with paper, I did it under dim florescent light and the highlights cleared very well.

Once dry, the plate is exposed in very much the same way as a paper print.

The development is all done in water but clears very quickly.

I did a 30 second soak. When the plate came out and was set to dry, it ran blue chemical off into the paper towel. I think this is normal.

The second development bath is a bit more aggressive with light agitation.

A few beginnings: Sizing Paper

This weekend, I started a few new things.

Sizing paper:

Sizing paper is a technique that is used to prepare a substrate for coating with an emulsion. The Internet is full of examples of different chemicals and materials used for sizing paper. I started with three of them.

1) (simple) Acrylic Fixative - I only read this on one site, but it seems to make sense.

I tried this method with both Canson - feuilles fineface 190g watercolor paper and some handmade Saa Paper from Northern Thailand.

So far, I have only coated the paper for Cyanotype prints, but the Saa paper benefited the most with sizing really preventing the Cyanotype emulsion from sinking in to the fibers during coating and making it much easier (and more efficient) to apply.

2) (medium) Gesso + Water - I used a 1:1 mix of Clear Gesso and Water

I tried this method also with both Canson - feuilles fineface 190g watercolor paper and some handmade Saa Paper from Northern Thailand. I love the texture it leaves the paper. The Saa paper was almost completely sealed and took the emulsion well.

3) (complex) Gelatin - I used stock standard Knox Gelatine.

I have yet to coat these papers with emulsion. But the process of sizing with Gelatin was interesting and a good learning experience. The Watercolor paper was easy with a full submersion in a cookie tray of gelatin.

The Saa paper did not take well to being submerged in gelatin. It was too fragile to remove without damage. I resorted to using a brush on method with a soft hake brush. The paper was on glass and a saturated it then VERY gently squeegeed it off and hung it to dry.

Mushroom Lumen Prints