16x20 unicolor drum devoloping negs

[Mac_4459]

Hi i have just got an Unicolor 16x20 drum and was wondering what chemical solution quantities would be needed to cover 4 x 8x10 film I have had some some success using the 8x10 version but the 16x20 looks huge almost size of a small uk dust bin the film i will be using varies from fp4,hp5,tmax, any advice thanks in advance Mac

[Bob Fowler]

Let me state from the get-go that I only use the 8X10 and 11X14 Unidrums and I don't know how much chemistry Unicolor calls for to cover a 16X20 print. Regardless, you'll need more solution for film than is "required" for paper.

My advice is to dilute your developer for one-shot use and calculate how much to use by the total square inches of film being processed. For example, it's been suggested that, regardless of dilution, you should have no less than 3ml of HC-110 per 80 square inches of film being processed. I tend to mix enough developer so that I'm using at least 5ml of concentrate, just so I don't push the exhaustion envelope, even if it means putting a lot of solution into the drum (see http://www.covingtoninnovations.com/hc110/).

Hope this helps...

[CXC]

I found some info on the Jobo website that says use 200ml in their 16x20 drum, and their 20x24 drum says on the outside to use 300ml. When you pour it in, it seems like way too little, yet it works.

[Mac_4459]

Thanks for all the info .. in the end i decided to use a whopping 800ml for 4x 8x10 negs fp4 1-3 dilution and it worked fine it prb seems overdose in amounts but id rather have more then less