[keesbran]

I have poured several A4 and two A2 size sheets with 750ml glop sensitized with this magic 'hardener #3' (di-Sodium-4,4'-diazido-stilbene-2,2'-disulfonate tetrahydrate) I received last week. In this glop I mixed a dilution of the powder as Charles wrote above. So in this 750ml is 4,5 gr diazo salt.

While waiting for them to dry I couldn't resist to do some tests.
I diluted another 3 grams of the diazostilbene in 100ml water. And with this I tried:

1. A gum print
I mixed the 3% diazo 1+1 with my regular 14 baumé pigmented gum and tried several exposure times. None where succesful. The gum allways ran off the sheet leaving a yellow stained image in the paperbase.

2. A PVA print
Same setup but now I took a 10% solution of pigmented Mowiol 4-88, a partially hydrolized PVA. This worked a little better. There was some hardening at very long exposure times and a trace of an image was left.

So far so good. Probably the concentration of the diazo must be higher to make this work, at the same time rendering it unusable by it's cost.

But then....

I took one of my 'normal' pigment sheets and brush sensitized it with the 3% diazo solution. I exposed it, dried it overnight (!) and processed it as a normal carbon print, transfered to a sheet of fixed glossy RC paper.

And...

It worked perpectly. Maybe the exposure time could have been a little bit longer, but it is pretty close to a normal printing time!

So I'm very happy with my investment in this powder!

I was allready used a to presensitized carbon because I used Halvor Bjørngård's Chiba method of ferric hardening. But that's more complicated because it is so sensitive to oxigen. I experimented with several temporary protective layers, other than the agar-agar Halvor describes.

More tests will follow.

Kees

-k