Film base thickness and flatness: Kodak T Max vs Ilford Delta

ymc226 · Sep 15, 2023

I don't print anymore but do scan with a digital camera. Water usage in California makes print washing less tenable for me and I donated all my enlargers. Tri X is my current B&W film on 120 but it seems to curl a bit when hanging to dry. In the future, I would like to try tabular films so would like a film base that is more scan friendly. Presently, I use a complete Negative Supply scanning set up for both 120 and 35mm which has good negative holders. Which film base would dry more flat and/or has a thicker base? I used to use Rodinal or HC110 15 years ago but I understand those have changed so currently, DDX is my sole film developer.

Steven Lee · Sep 15, 2023

I have the same Negative Supply kit and I have zero curling problems with Kodak C41 films and Ilford B&W films, including tabular ones like Delta. Also, I can recommend two easy tricks to increase film flatness with your holder:

Make a tight roll with emulsion facing outward and keep it like that for 10 minutes prior to scanning.
Buy some camera sealing foam on Amazon and glue it inside the film holder on both sides of the gate. It will provide additional support for film, eliminating sagging and improving flatness.

These two combined give me essentially perfectly flat surface, similar to sandwiching film between two pieces of ANR glass, while keeping the speed and convenience of the Negative Supply holder.

Good luck

Prest_400 · Sep 16, 2023

This is interesting. Ilford film seems to use the same acetate base across their lines. I nowadays just shoot mostly it, HP5 lies very flat in 120 and 35mm Kentmere/APX and so gives no issues. I have a couple Delta 400 120 to develop this weekend but I expect the same.

For Kodak it can be interesting. They converted Kodacolor Plus and Portra 800 to ESTAR (Polyester) in 35mm, in 120 Gold 200 and Ektachrome were readily introduced on ESTAR but there isn't really much, at least in the latter's datasheet. Unsure if in the longer term Kodak will begin to use ESTAR more broadly compared to acetate. I tend to bring it into discussions around as its dimensional and archival stability is much better compared to acetate.

B&W Polyester film wise, in rollfilm, it's just Fomapan in 120 nowadays that I have been using. Feels thinner but it is stronger and can have an initial curl. AFAIK the curl is not just due to the material but other factors as well. A few days below some weight does help a lot in flattening it.

Sal Santamaura · Sep 16, 2023

The base thickness of 120 TRI-X is 3.9 mils. The base thickness of 120 TMAX films is 4.7 mils. TMAX are the only tabular grain films extant. Delta films (in 120 they're on a 4.3 mil base, except for the 3200 version, which is 5 mils) are core-shell technology.

In my experience, there's no correlation between base thickness and flatness of acetate negatives after drying. The latter varies widely depending on age of film, process specifics, ambient humidity and individuals' developing routines.

ymc226 · Sep 16, 2023

Steven Lee said:
I have the same Negative Supply kit and I have zero curling problems with Kodak C41 films and Ilford B&W films, including tabular ones like Delta. Also, I can recommend two easy tricks to increase film flatness with your holder:

Make a tight roll with emulsion facing outward and keep it like that for 10 minutes prior to scanning.

Buy some camera sealing foam on Amazon and glue it inside the film holder on both sides of the gate. It will provide additional support for film, eliminating sagging and improving flatness.

These two combined give me essentially perfectly flat surface, similar to sandwiching film between two pieces of ANR glass, while keeping the speed and convenience of the Negative Supply holder.

Good luck

Thank you Steve. Those are great suggestions. That is great that Delta works out fine for you. I bought a ton of Tri X so have go through it before I can try Delta or their other conventional B&W film.

ymc226 · Sep 16, 2023

Sal Santamaura said:
The base thickness of 120 TRI-X is 3.9 mils. The base thickness of 120 TMAX films is 4.7 mils. TMAX are the only tabular grain films extant. Delta films (in 120 they're on a 4.3 mil base, except for the 3200 version, which is 5 mils) are core-shell technology.

In my experience, there's no correlation between base thickness and flatness of acetate negatives after drying. The latter varies widely depending on age of film, process specifics, ambient humidity and individuals' developing routines.

Thank you both Prest and Sal for bringing it to my attention that thickness does not relate to flatness. I can only eventually try TMAX and Ilford and see what happens.

Ivo Stunga · Sep 17, 2023

Sal Santamaura said:
In my experience, there's no correlation between base thickness and flatness of acetate negatives after drying.

Came to state pretty much this - the curling isn't base thickness dependant. This is obvious when doing BW reversal and massaging all the films the same. I find it depends on the age and finishing of the film: how tight it's rolled and for how long.
I've had perfectly flat triacetate of various thickness (Ferrania, Ilford, Foma), I've had curled PET into oblivion (Adox CHS 100 II and Ukrainian resolt Aviphot).
I've had poorly behaving triacetate (if curling occurs, it's usually triacetate in my experience) and perfectly flat PET (Adox/Rollei converted Aviphot, for example).

Where base material and dimensional/archival stability of PET comes into play, however, is projection: triacetate will bulge and deform under the heat of projection lamp, but PET will keep intact, making it best choice for projection because of 1) clear base and this 2) mechanical endurance.

250swb · Sep 17, 2023

ymc226 said:
I don't print anymore but do scan with a digital camera. Water usage in California makes print washing less tenable for me and I donated all my enlargers. Tri X is my current B&W film on 120 but it seems to curl a bit when hanging to dry. In the future, I would like to try tabular films so would like a film base that is more scan friendly. Presently, I use a complete Negative Supply scanning set up for both 120 and 35mm which has good negative holders. Which film base would dry more flat and/or has a thicker base? I used to use Rodinal or HC110 15 years ago but I understand those have changed so currently, DDX is my sole film developer.

Any Ilford film dries considerably flatter than Kodak in both 35mm and medium format, and Ilford Delta films doubly so. And DD-X is the perfect developer for the Delta films as a datum point but they also work well with Pyro developers. Ilford do now make a copy of HC-110 called Ilfotec HC which even uses the same dilutions.

Alan Johnson · Sep 17, 2023

250swb said:
Any Ilford film dries considerably flatter than Kodak in both 35mm and medium format, and Ilford Delta films doubly so. And DD-X is the perfect developer for the Delta films as a datum point but they also work well with Pyro developers. Ilford do now make a copy of HC-110 called Ilfotec HC which even uses the same dilutions.

That is my experience too with Delta 100 vs 100 Tmax. Delta dries flat, Tmax curls across the width.

Tom Kershaw · Sep 17, 2023

250swb said:
Ilford do now make a copy of HC-110 called Ilfotec HC which even uses the same dilutions.

Ilfotec HC has been made for a while; I have negatives developed with it from 2005.

Kino · Sep 17, 2023

I find that leaving film to hang and dry for a week helps with any film base flatness. Not everyone wants to wait that long, but I have found it to be worth the wait...

Film base thickness and flatness: Kodak T Max vs Ilford Delta

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