T-Max 100 UV layer and Salt Printing

[Tom Nutter]

Can some one point to a link or provide a brief explanation of what the UV layer now present in Tmax films means for contact printing negatives on salted paper? Salt printing is something I've been wanting to try...so, will tmax 100 not work at all?

Also, I'm wondering how a cold-light enlarger head is affected by this change in the film.

This may all be old news, I'm not sure, but I have been out of the darkroom for a number of years.

Thanks!

 

[sanking]

Can some one point to a link or provide a brief explanation of what the UV layer now present in Tmax films means for contact printing negatives on salted paper? Salt printing is something I've been wanting to try...so, will tmax 100 not work at all?

Also, I'm wondering how a cold-light enlarger head is affected by this change in the film.

This may all be old news, I'm not sure, but I have been out of the darkroom for a number of years.

Thanks!

The coating on Tmax-100 film basically blocks about three full stops of light. So, if your exposure with another film without the coating was 10 minutes, it would be 80 minutes with Tmax-100.

That would be true for salt printing, and all other forms of alternative printing that expose with UV light.

Sandy

 

[Denis K]

I know nothing about contact printing negatives on salted paper but based on your concern I assume it involved using UV light as the light source for exposing the contact print. I also can't speak for Tmax 100 but do have a bunch of rolls of Tmax-400 (TMY-2) and I measured the density of a clear section of one of my previously developed rolls. I used a X-Rite 361T, which has both an ortho and UV channel. The density measurements were:

Ortho Channel: 0.20
UV Channel: 0.46

This would imply to me that the excess density at UV is about 0.26 log units which is a bit less than one stop. If Sandy is correct that Tmax incorporates a 3-stop UV filter, I would have to conclude that it washes away during development or else it only rolls off light shorter than the UV light used in my densitometer. I don't know what the center frequency is of the UV channel, but I would guess that X-Rite picked a band that is typically used in the prepress world, which might be the same as your salted-paper work.

Denis K

 

[sanking]

I know nothing about contact printing negatives on salted paper but based on your concern I assume it involved using UV light as the light source for exposing the contact print. I also can't speak for Tmax 100 but do have a bunch of rolls of Tmax-400 (TMY-2) and I measured the density of a clear section of one of my previously developed rolls. I used a X-Rite 361T, which has both an ortho and UV channel. The density measurements were:

Ortho Channel: 0.20
UV Channel: 0.46

This would imply to me that the excess density at UV is about 0.26 log units which is a bit less than one stop. If Sandy is correct that Tmax incorporates a 3-stop UV filter, I would have to conclude that it washes away during development or else it only rolls off light shorter than the UV light used in my densitometer. I don't know what the center frequency is of the UV channel, but I would guess that X-Rite picked a band that is typically used in the prepress world, which might be the same as your salted-paper work.

Denis K

We are discussing two different films. TMY/TMY-2 does not have a coating that blocks UV light. Tmax-100 does. The UV blocking does not wash away.

Clay Harmon and I were the first to observe and report this, quite some years ago, but since that time the problem has been pretty well documented. My recollection is that Clay and I both observed the UV blocking issue independently, but an exchange of information validated our findings. Much later some fellow at RIT published a chart on this, but I don't have the URL any more.

Sandy King

 

[Tom Nutter]

So, if I use most other films like hp-5 plus, Tri-X, Plus-x, Acros, I can avoid the problem. I'll just use the 40 sheets of TMX I have for something else.

Thanks folks.

PS--Except perhaps Plus-x is no longer available in sheet form.

 

[sanking]

So, if I use most other films like hp-5 plus, Tri-X, Plus-x, Acros, I can avoid the problem. I'll just use the 40 sheets of TMX I have for something else.

Thanks folks.

That is correct. Most sheet film does not have the UV blocking coating. But I can not speak to every one of them. However, to the best of my knowledge and testing the only film that has the blocking is Kodak Tmax-100.

Sandy King

 

[smieglitz]

You can see the effect here comparing Old TMY, New TMX, and HP5+:

 

[Denis K]

We are discussing two different films. TMY/TMY-2 does not have a coating that blocks UV light. Tmax-100 does. The UV blocking does not wash away.
Sandy King

Sandy, Just for the record I measured the Ortho and UV transmission of TMX last night on an unexposed but fixed piece of TMX 120 film stock. Again this was done with the Ortho and UV channels of my X-Rite 361T densitometer. The results of course confirm your finding, at least in the 120 film emulsion. The reading were:

Ortho Channel: 0.07 Log Units
UV Channel: 1.22 Log Units (i.e. a boat-load)

Denis K

 

[sanking]

Sandy, Just for the record I measured the Ortho and UV transmission of TMX last night on an unexposed but fixed piece of TMX 120 film stock. Again this was done with the Ortho and UV channels of my X-Rite 361T densitometer. The results of course confirm your finding, at least in the 120 film emulsion. The reading were:

Ortho Channel: 0.07 Log Units
UV Channel: 1.22 Log Units (i.e. a boat-load)

Denis K

Denis,

Thanks for the information. Yes a boat load of UV blocking. More like four stops rather than the three stops I suggested.

So if your base exposure with most films for UV processes is 5 minutes, with Tmax-100 the exposure would be 80 minutes!!

Sandy