Selective bleaching

[eddie]

I have a negative with a scratch... Of course, it's across part of the sky, giving me a black line through a white cloud. I have potassium ferricyanide, and I'd like to bleach out the cloud (and line) on the prints I've made. I've never done this before, so have a few questions/assumptions:
1- I assume I should re-wet the paper.
2- I plan on applying the PF with a cotton ball, and/or q-tips.
3- After bleaching, I should re-fix, wash, etc, as normal.
4- How should I mix the PF solution? How many grams PF powder to ounces of water?
Thanks.

 

[Vaughn]

I suggest not re-wetting the paper. That way, the bleach will not diffuse away from the scratch. Get the scratch bleached out first using a very small brush, such as a 000 spotting brush. Then you might want to wet the whole print and attack the general area (cloud). Put the print on a slanted piece of glass in the sink. and use a hose or beaker of water to control the action of the bleach.

It will be an interesting experiment (have several copies on hand!). But in the end, you might decide the best thing to do is either to rephotograph, or just forget about the negative/image and move on.

Vaughn

 

[keithwms]

My first suggestion is to enlarge to ortho film, to the size at which you want to print. You can retouch the ortho film quite easily. You could also make a paper neg and retouch the back surface of that with a pencil (and even erase!)...

Selective bleachign can be done but generally I think you want to make yourself a neg that gives you a fighting chance. Bear in mind that in the interneg, the black line will be white... which can be filled in... and it's usually easier to make something light go dark than vice versa.

 

[dpurdy]

Trying to bleach out a scratch without bleaching out a fair amount around the scratch is pretty difficult. Hopefully your retouching skills are good. I sometimes bleach out very small spots. For that I mix a strong bath of Potassium Ferricyanide so that I can get it in one touch and then I use a 000 spotting brush. If I was going to try to bleach out a thin line I would use the little brush instead of a q tip which is going to bleach a wide swath. I would do it with the print wet with fixer and very squeegeed off so that there are no drops of anything to make the bleach run.
Dennis

 

[Andrew Moxom]

there are many schools of thought on this.... I would keep the print wet, and flat, and then bleach the line a fine brush... squeegee the local area, and apply the bleach. Leave it for no more then 10 seconds, and then wash it off quickly with a hose or faucet sprinkler swabbing the area well afterwards to prevent any running. Squeegee again and repeat until the line is gone, and retouch as necessary.

 

[spijker]

I'm doing quite a bit of selective bleaching lately as part of an advanced darkroom course. First we're soaking our prints in water for a couple of minutes and then in fix for about a minute. The bleach is a fairly weak mix of potassium ferricyanide with a bit of fix. We use about a teaspoon PF for half a liter of water plus about 20 ml of fix (mix is not too critical). Fix is required to activate the potassium ferricyanide. You can also use Farmer's Reducer which is essentially the same thing (PT + fix).

After the initial soak, fix and a quick rinse, put the print on a board over the sink and squeegee the print so that the bleach cannot spread by itself. Use a brush to apply the bleach. The brush size depends on the area to bleach. Don't let the bleach sit on the print for too long (> 30s) but rinse it off with water from a hose or tap. After some bleaching put the print back into the fix for about 1 minute to avoid yellow stains. Rinse and bleach more if necessary. Be aware that the bleach works much faster on highlights than lowlights due to the much higher amount of silver in lowlights. Even run-off water with bleach will bleach highlights areas of the print. So be carefull with rinsing. After the bleaching, fix and wash as you normally do with printing.

Good luck,
Menno

 

[eddie]

Thanks for all the input. I have 4 20x24 prints, of the negative, to try it on. The negative is a 4x5 which was copied from a 4x5 color transparency. Even at 4x5, retouching the negative isn't gonna happen... the scratch is so small I can barely see it with a loupe. My spotting skills are pretty good (even though I hate it), so I think I can get this done properly.