HP Combi & 12 Negatives in one tank

[ki6mf]

Any one developing two images with the plastic back to back in the HP Combi? Its designed to take 6 negatives however the film holders will accommodate 12 negatives. Thoughts Issues not recommended etc? I have been doing up to 6 images, depending on exposure, at a time in d-76 diluted 1-3 with N times being 14 Minutes!

[77seriesiii]

the other night I did 6 and I thought that I had separated them, I didnt. However I was lucky they were back to back. Seemed to work. I know that few people to include Bob Saloman from HP marketing, have attested to the fact that a combi can take 12.

what kind of developer are you using?

Erick

[Bob Salomon]

Yes you can do 12 black and white negatives back to back in the CombiPlan tank. Some people pre-wet the film to prevent them from sticking back to back and some users used a piece of fiberglass window screen, cut to size, between the two sheets. No additional developing time or chemistry is required when doing 2 sheets back to back in the tank.

Do not do this with color film as you will not get the backing off.

[ki6mf]

Thanks for the note It does help when there are lots of negatives to process. The units (I have 3 tanks) work very well. I use D76 diluted 1:3.

[Bjorn Nilsson]

Just make sure that the 1:3 D76 can cope with that much film area. There is a minimum of developer required.

//Björn

[jp]

I'll have to try loading the negatives back to back sometime. I've processed about 75 pieces of film so far in this.

I have two tanks now, so either way, 12 at a time is plenty for me currently as I can't dry much more than that simultaneously, but I could address that.

One thing I have noticed about the system; don't push the orange clip down too far that holds the film. One click is fine. Too much pushing distorts the film and makes it pop out of the edge guides too easily.

Inversion agitation can be fairly gentle and leisurely.

I wish I could fill and drain the tank faster. I'm open to suggestions for this. For film developing, this is compared to Paterson reels/tanks for 35mm/120 film.

I can load it while it's still wet; this is very handy.

I would buy a bigger tank such as one that held two film carriers and filled/drained faster. This would be a good accessories for use after major photography outings, or when playing catch-up. A separate spigot for air venting, with a ball check valve like a racing fuel cell filler neck would speed up the process of filling and draining and could prevent messes when inverting.

[Michael N. Meyer]

I do 12 sheets in my CombiPlan tank all the time. Works fine.

The only issue I have doing this is that after fixing I need to give each individual negative a dunk in developer to remove the anti-halation layer on the film base (at least I think that is what it is). I then redunk in fixer before washing. Placing a nylon screen between the sheets might fix this, but I haven't the patience when loading the tank.

-m

[Peter Latner]

Filling and draining these tanks quickly is impossible with the small funnels and openings on these tanks. I have four Combi Tanks, which I set up beforehand, one with water for a pre-soak, one with developer, one with stop, one with fix. Once the film is loaded, I immerse it into the pre-soak for a minute or two, let it drain for a few seconds, drop it into the developer, quickly snap on the lid, turn on the lights and begin agitating. When the development time is up, I switch off the lights and immerse in the stop, and then fixer. While it's fixing, I change the water in the pre-soak tank and use it for washing and hypo-clear. Works very well. The only way I'd use those funnels is for a 15-20 minute development time--and even then I'd worry about uneven development.

I wish I could fill and drain the tank faster. I'm open to suggestions for this. For film developing, this is compared to Paterson reels/tanks for 35mm/120 film.

[Bob McCarthy]

I do 12 sheets in my CombiPlan tank all the time. Works fine.

The only issue I have doing this is that after fixing I need to give each individual negative a dunk in developer to remove the anti-halation layer on the film base (at least I think that is what it is). I then redunk in fixer before washing. Placing a nylon screen between the sheets might fix this, but I haven't the patience when loading the tank.

-m

I've run across the same issue, anti-halation layer on the back of the film not completely dissolving. It there a better way than a re-dunk in developer and re-fixing??

bob

[Gem Singer]

Bob,

Just re-fix for a few extra minutes. No need to put the film back into the developer. Film will not re-develop once it has been fixed