View Full Version : ABS Film Development Tubes; How to separate

Eric Woodbury
26-Mar-2017, 11:56
I've been using ABS (aka BTZS) tubes for my 45 and 57 film. Now I've made some 3 inch (75mm) diameter tubes for 810. This is the simplest version of construction; simply a tube with film and a cap and reservoir on the other end. Slide together, not threads. I'm worried that once I put them together with developer in them I won't be able to separate the two parts for the next step.

I see three possible means to ameliorate this issue and wondering what you all are doing.

1) taper the tube where it engages the fitting in an effort to make the fit sloppy without light leaks
2) lubricate the junction with something that doesn't get into the 'mix'
3) add some means to inject water pressure to the inside to 'blow' the two pieces apart.

Thanks in advance. LF'rs are the best.


26-Mar-2017, 12:46
I would rough the end of the male tube with sandpaper, for the length of the overlap joint. Wipe it with alcohol so as not to get plastic dust in the mix. It might take a few uses to "mature" the fit of the joint and get all the dusties out.

Why not use pipe threads? I use a flexible Fernco-type coupling with PVC threaded fittings on the end. This gives me 2 inches longer tube length, so I can do semi-stand development and assure myself the film is 100% immersed. I used more than 100% brimful volume of working solution developer, which is the reason I needed a longer (increased volume) tube.

Michael Kadillak
26-Mar-2017, 12:55
Easy one Eric. I use a single 3" tube section and glue a hard cap on one end and using my infrared monocle I put the film in the tube emulsion side in and pour the developer in on the fly. They sell a rubber cap for these tubes at the hardware store that comes with a clamp that you can take off because you do not need it. The rubber cap ensures you will always easily be able to remove it and it and you can use the clamp if you so chose. I use my tubes for RAD (Reduced Agitation Development) for 4x5, 5x7, 8x10, 8x20, 11x14 and 12x20. The infrared monocle surely makes it easy to see what needs to be done sans any concern of fogging film. I do not like the long multiple sections because of the potential for connection leaks. KISS. At the end of the day it is about results.

26-Mar-2017, 16:19
I've been using 4x5 BTZS tubes but recently figured out that the caps only held 60 ml which ended up as 6 ml of Ilfosol 3 @ 1:9 where the developer spec sheets indicated I should have 8 ml per sheet (64 4x5 sheets for 500 ml). So I needed a bigger cap. I wanted to slow down the development time by going to 1:14 (90 ml of solution) anyway so I decided to look at ways of increasing the cap size.

My first attempt was a friction fit with 1 1/2 inch ABS fittings (straight coupler) similar to what you're proposing I think. I got it to work but the challenge was compressing the air in the tube when joining the cap the two sections in use. The tighter the fit, the less developer leaking but it acted like an air piston and difficult to compress. Others have got around this with a rubber clamping sleeve.

What I ended up using was replacing the straight coupler with threaded male and female joining couplers (about $1.90 Can each I think) which lets me gradually join the two pieces. Obviously you'd need bigger diameters for the 8x10 but the principle would be the same. I haven't noticed much in the way of leaking but I can add a rubber washer if I need to and if I need more developer I can just make a longer cap. Here's a picture showing the two ends - hopefully you can make it out ok. Notice the male end is on the film side so I can grab the film easier.

Good luck