Unsharp masking & colour balance

[SeanEsopenko]

I'm introducing cross curves with my unsharp masks when printing RA4 in the darkroom. I'm trying to figure out if it could be the difference in colour between the FP4+ film base and film emulsion or if I have the enlarger's dichroic wheels set incorrectly during the contact print onto the masking film, or both.

The FP4+ I use for masking has a slight green colour to it which I think is the cause for magenta shadows that I get when masking. I also believe that I'm incorrectly exposing the unsharp mask by using the same colour balance that I use to make a balanced (yet high contrast) unmasked print. I get strange looking yellows compared to the unmasked print, along with the magenta shadow regions. The yellows look kinda unreal and "tone mapped" compared to the tones of the rest of the image.

I could go through the painstaking process of doing a sort of masking ring-around, changing the colour balance of the enlarger for many different masks to see what it does but I thought I'd ask people here on the forums if they'd like to share their own thoughts before I do such a time consuming exercise.

I'm pretty sure the magenta shadows are due to the film base of the mask being a different colour than the black, developed & fixed emulsion (which is why a completely different colour balance is required for a masked vs unmasked print). I have no clue how to solve that specific problem.

[Drew Wiley]

Not all dev/fix combination effectively clear the residual M of the antihalation dye.
I have been doing fine with HC110 dev and TF4 fix. The stain gradually fades or can
be UV bleached out. The color of the film base itself is virtually neutral - you should
be about to get it down to around 2cc of yellowish whatever (easily nulled out during
printing). A brief rinse in Farmer's reducer will clear any base fog if necessary, but you
have to be careful not to overdo it. None of this is related to color balance issues
exposing the mask to begin with, which requires setting the colorhead to a true daylt
K temp (preferably using a color temp meter), then nulling out the orange mask using
a lt orange filter, and preferably also a lt YG filter to compensate for the depressed
green sensitivity of the film also. This will result in a pinch of ND obviously, but is more
staightforward than the options. But any way you look at this, you have to pay your
dues first, just like learning the chords on a piano. It takes a fair amt of testing with
your specific equipment.

[SeanEsopenko]

I spent more time on this issue. I've got some masks I did a while ago with 4x5 FP4 that I was registering by eye and they don't have the pink/purple base colour. That's why I brought up this issue in a thread. They appear to have had all the antihalation dye to rinse out fine. I have some 5x7 FP4 I'm using now because it makes it easier to use with a pin registration device but the anti-halation dye isn't rinsing out.

I thought maybe it was because I was using a different developer (Ilfosol 3 instead of D76 like before) so I went back to D76 and it still didn't fix it. I pre-soaked the negatives for 5 minutes instead of 30 seconds like I usually do and it still didn't fix it. I'm now under the impression that I just won't get all the anti-halation out of this box of 5x7 FP4 and that Ilford changed something in their production (the 4x5 I was using for masking before was expired when I purchased it).

I'm thinking of trying Tmax 100 because I've heard multiple accounts that it's anti-halation dyes rinse out easier. Anybody care to share their experience as to which films rinse out to a neutral film base the best?

[D. Bryant]

I spent more time on this issue. I've got some masks I did a while ago with 4x5 FP4 that I was registering by eye and they don't have the pink/purple base colour. That's why I brought up this issue in a thread. They appear to have had all the antihalation dye to rinse out fine. I have some 5x7 FP4 I'm using now because it makes it easier to use with a pin registration device but the anti-halation dye isn't rinsing out.

I thought maybe it was because I was using a different developer (Ilfosol 3 instead of D76 like before) so I went back to D76 and it still didn't fix it. I pre-soaked the negatives for 5 minutes instead of 30 seconds like I usually do and it still didn't fix it. I'm now under the impression that I just won't get all the anti-halation out of this box of 5x7 FP4 and that Ilford changed something in their production (the 4x5 I was using for masking before was expired when I purchased it).

I'm thinking of trying Tmax 100 because I've heard multiple accounts that it's anti-halation dyes rinse out easier. Anybody care to share their experience as to which films rinse out to a neutral film base the best?

Have you tried a water pre-soak before development. That usually washes out most if not all of the AH dye. Also are you using a hypo-clearing agent? That can aid dye clearing as well.

Don Bryant

[Nathan Potter]

I use Tmax 100 in a small tube with D76 and continuous agitation. No presoak but hypo clear separately in a tray for up to 8 min (usually 5 min). Most always virtually clear but I haven't used a spectrophotometer to get an accurate reading - might soon though.

But I shoot a CC color matrix with every print so any tint is compensated for automatically. I've always thought I was easily below 5CC of tint but I do Ilfochrome which I find fairly tolerant of small CC changes. Dunno about RA4 sensitivity.

Nate Potter, Austin TX.

[SeanEsopenko]

Have you tried a water pre-soak before development.

Yeap that's standard issue and I even tried extending it to 5 minutes with slight agitation

Also are you using a hypo-clearing agent? That can aid dye clearing as well.

Haven't tried this, thanks for the tip. You think the hypo-clear is reusable or is it one-shot? If it's reusable about how long can the mixed solution sit in a squeeze-bottle container?

I use Tmax 100 in a small tube with D76 and continuous agitation. No presoak but hypo clear separately in a tray for up to 8 min (usually 5 min).

I notice a corellation here with Don's suggestion so I'm trying the hypo clear for sure with my next mask. What does the continuous agitation do for you and how come you use it?

But I shoot a CC color matrix with every print so any tint is compensated for automatically. I've always thought I was easily below 5CC of tint but I do Ilfochrome which I find fairly tolerant of small CC changes. Dunno about RA4 sensitivity.

Currently the residual antihalation tint causes the hilights to go out about 7-10CC into the cyan end when the shadows are perfectly balanced. Much more if it's a strong mask for extremely contrasty negatives. I find that good balancing requires my own RA4 prints to be within 1-2 CC points.

I'm not developing at standard temperatures nor speeds thought because my CAP-40's been regeared to 1:05 minutes at 92F. That's the closest pulley I could find to 45 seconds and the 92F is according to a kodak technical doc I found. I get prints without cross-curves but I don't think the deviation from standard development makes it easier.

[Drew Wiley]

The combination of FP4 and 76 always seems to leave a little antihalation dye left
behind. I typically would get around 2cc M. Really a small amount; but HC-110 seems to work better at removing it. The greenish color of the FP4 emulsion probably has nothing to do with it. But you will need to learn how to balance your
masks for the presence of the orange mask in the color neg itself as well as the
reduced green sensitivity of the pan emulsion.

[SeanEsopenko]

The combination of FP4 and 76 always seems to leave a little antihalation dye left
behind. I typically would get around 2cc M. Really a small amount; but HC-110 seems to work better at removing it. The greenish color of the FP4 emulsion probably has nothing to do with it. But you will need to learn how to balance your
masks for the presence of the orange mask in the color neg itself as well as the
reduced green sensitivity of the pan emulsion.

Can I use the CC settings that yield a balanced, unmasked print as a starting point for the mask's colour balance?

Also, this acidic, bright yellow in the van is due to being unbalanced when creating the mask, isn't it? Let me walk myself through a correction and tell me if I have it right?

I need less yellow in the van (which is bright, so therefore is targeted by the mask) so that means the mask needs to be denser in the yellow regions. The way I do that is by increasing the opposite, blue? So I'd turn down the yellow when contact printing/creating the mask? Do I have that right?

[Drew Wiley]

Oh ... and TMX does clear better ... the stain will be pretty obvious after fixing but
washes out completely a few minutes afterwards. It makes an excellent masking film except for the possibility of it becoming scarce if Kodak goes blinko.

[Drew Wiley]

When making a mask it's easiest to balance the colorhead to "daylight" - around
5000 to 5500 K - then add a light orange filter over the lens to null out the orange
mask, plus a very light yellow-green to balance the pan film green sensitivity deficiency. This get you to a reasonable starting point. Best to have a color temp
meter handy. I'm helping my wife cook right now, so may have to answer the rest
of your question tomorrow ....