Film Curl

[Curt]

My 120 Adox 25 film curls like it came right out of the beauty parlor. I know now why I like sheet film so much!

I wonder what they do in the manufacture? Or is it inherent in the base material? At this rate I'll have to get a glass carrier!

 

[timeUnit]

Interesting. My first roll of Adox/Efke 50 (should be same base) is very nice and flat. The base is a bit thin and one could call it "flimsy" or similar, but it does not curl. I've had more issues with llford Delta 3200.

 

[Photo Engineer]

Film curl is a function of the emulsion layer, and any layers coated on the back of the film support. These must be balanced and have anti-curl and 'softening' agents in them. Doing this is an art that requires precise control from batch to batch.

Some companies can do it well, and others cannot. Some companies have huge batch-to-batch variation.

Curl also is increased by changes in humidity and by how old the roll of film is. Old rolls develop a 'set' to them with more curl. In addition, the thickness of the support is important. Support ranges from 2 mil to 7 mil (that is an 'English' measure). The thinner the support wrt emulsion thickness, the more the curl.

PE

 

[roteague]

PE,

I have an issue that perhaps you could explain to me. I have used Efke PL100 in the past but I found that when I put the exposed film back into the box, it all sticks together. This has caused me to have to keep all the paper backings, which is a real pain. The humidity level where I live is around 74%. I've had the same problem with Ilford Delta 100, but never with Fuji Velvia. I've gone to using Fuji Acros in QuickLoads in order to shoot B&W.

Sorry for changing the subject,

 

[Gerald Koch]

I have often wondered why 120 film base is thinner than 35mm. You would think that the larger size of the 120 format would require a thicker base.

 

[roteague]

I forgot to mention the problem I have been having is with 4x5 film.

 

[Photo Engineer]

Replies to both of you.

Robert, there is probably something off in the formulation of the film or the backing that promotes this tackiness. An excess of humectant, to protect from cracking will sometimes do this. Another thing is that Kodak and Fuji add a roughening agent to the back side of the film to both prevent this and to promote retouching by giving the back a 'tooth'. This prevents sticking. So, sometimes economy films are just that!

Gerald, by my measuremnt with a micrometer just now, the following films are exactly 5 mil in thickness - 120, 220, 35mm. Brands measured, Ilford and Kodak.

By comparison, a sheet of 4x5 film is just a tad over 7.5 mil (Kodak), and a sheet of raw Estar with no coating is 7 mil (off brand raw Estar with subbing only).

PE

 

[roteague]

Thanks PE. Your reply is greatly appreciated. I guess that I will stick with Fuji Acros for the time being.

 

[Photo Engineer]

An afterthought for Robert, many films from the second tier of manufacturers or the third tier, still use formalin or other older hardeners. Such films are often actually softer, but more prone to cracking and therefore require a higher level of humectants such as glycerine. The glycerin can wash out and therefore not cause tackiness, but sometimes they use a polymer such as polyethylene glycol or some such and that might impart tackiness. IDK for sure. Just in case, you might try an extended wash and a decrease in the amount of photo-flo concentration. That might help.

IIRC, there was at one time a family of anti-tackiness sprays or dips that supposedly prevented this type of problem way back in the 'old days'.

PE

 

[Photo Engineer]

Thanks PE. Your reply is greatly appreciated. I guess that I will stick with Fuji Acros for the time being.

One of my superior officers in the AF was Robert Teague from Texas. He was really into photography.

Any relative?

PE

 

[roteague]

One of my superior officers in the AF was Robert Teague from Texas. He was really into photography.

Any relative?

PE

Not that I am aware of. I am from Texas, but I was an enlisted man in the Army. I did have an uncle, named Bill, who was an Air Force officer - I remember he took a lot of photos, but since he passed away 10+ years ago, I don't really know.

 

[Photo Engineer]

Not that I am aware of. I am from Texas, but I was an enlisted man in the Army. I did have an uncle, named Bill, who was an Air Force officer - I remember he took a lot of photos, but since he passed away 10+ years ago, I don't really know.

Whoops, you are right, Bill Teague. I'd bet it was your uncle.

He had one or two brothers or some cousins IIRC, and one was in government (Texas senator or something?) and another who was also in the AF. Anyhow, I knew of 3 Teagues at the time, but only one was in my unit. He was a Capt or a Major in 1960. I believe he was just promoted from Capt to Maj. He was my boss for several months before I was transferred.

PE

 

[Gerald Koch]

Concerning my question as to why 120 format film base is thinner than 35mm, I found the the following.

Efke and Forte use 125 um base for 35 mm and 100 um for 35mm.
Kodak Tech Pan uses 4 mil base for 35 mm and 3.6 mil for 120.

As I said this is counter-intuitive since 120 format film must span a much wider opening in the enlarger's carrier without sagging.

 

[roteague]

Whoops, you are right, Bill Teague. I'd bet it was your uncle.

He had one or two brothers or some cousins IIRC, and one was in government (Texas senator or something?) and another who was also in the AF. Anyhow, I knew of 3 Teagues at the time, but only one was in my unit. He was a Capt or a Major in 1960. I believe he was just promoted from Capt to Maj. He was my boss for several months before I was transferred.

PE

Could be, I remember Bill being a Major when he was stationed in Florida (1963 or so) - but, he was at home in Texas. My father (Roy) was in government; he worked for the Immigration and Naturalization Service (INS). I had another uncle, Glenn, but I don't remember what he did for a living. I actually had another uncle as well, Sidney, but he was killed on D-Day 1944 - AAF pilot I believe. They are all gone now. All of my family, except me, is in Texas.

Small world!!!!

 

[Photo Engineer]

Concerning my question as to why 120 format film base is thinner than 35mm, I found the the following.

Efke and Forte use 125 um base for 35 mm and 100 um for 35mm.
Kodak Tech Pan uses 4 mil base for 35 mm and 3.6 mil for 120.

As I said this is counter-intuitive since 120 format film must span a much wider opening in the enlarger's carrier without sagging.

Gerald, the line above about Efke and Forte is not clear to me. Could you repost that or clarify it?

Tech Pan uses thinner base than the 5 mil for other films does surprise me, but the use of 3.6 mil for 120 does not surprise me. There may be a need for thin base to allow for the paper backing in some instances. IDK. Maybe something about the applications for Tech Pan require a thinner base.

I know that they even make 120 on 2 mil support. It was / is used by NASA on space flights to conserve weight when film is used in large quantity and weight allowance is at a premium. Very thin film stock was used on the trips to the moon for just this reason. Also, special films were tested to check out the volatility of solvents and plasticizers in the vacuum of space.

So, there is no hard and fast rule, I would say, except for the fact that run-of-the-mill consumer and professional films fall into the 5 and 7 mil range for support thickness, and thickness depends on use, size and sometimes the strength of the support.

Acetate support is often thicker than estar support just because of the greater strength of estar per unit thickness. I've seen this in some applications.

PE

 

[Photo Engineer]

Could be, I remember Bill being a Major when he was stationed in Florida (1963 or so) - but, he was at home in Texas. My father (Roy) was in government; he worked for the Immigration and Naturalization Service (INS). I had another uncle, Glenn, but I don't remember what he did for a living. I actually had another uncle as well, Sidney, but he was killed on D-Day 1944 - AAF pilot I believe. They are all gone now. All of my family, except me, is in Texas.

Small world!!!!

Yes, small world. It finally came to me.

Bill referred to a relative named Olin Teague on several occasions. IIRC he was also with the government. Does that strike a chord with you?

PE

 

[Curt]

It's not something I haven't seen before and I did take the roll to a hotter room for drying. By curling I do mean width and not length. I would call it cupping if it were wood. I haven't tried the other Adox films yet but in the past I haven't had any problems printing, I was just surprised how much and how resistant to laying flat they were.
Thanks

 

[roteague]

Bill referred to a relative named Olin Teague on several occasions. IIRC he was also with the government. Does that strike a chord with you?

No, I haven't heard that name before. But, it could have been one of his cousins; I'm not familiar with that side of the family.