making your own processing tubes.

**Mark Tweedie** · 13-Jan-2006, 06:08

I recently experimented with making dev tubes from 40mm ABS tubing (available from plumber's merchants but not B&Q) here in the UK. The results have been excellent and economical. A couple of things I learned and wished I had known before:

1) ABS tubing is rougher on the inside than the outside (which is perfectly smooth). Any roughness can be removed with steel wool (not sand or glass paper as this will embed grains in the plastic and guarantee scratches) prior to assembly. I spoiled a couple of negs before I realised the interior of the tube was the problem. The wet negative is sucked tightly against the tube and when it is removed any protrusions will be certain to damage the film.

2) I used a modification of a plan I found on the net (I will post the url when I find it again). This plan uses three baffles as a light trap at the end where the chemicals are poured in to allow use in daylight. Be aware that ABS is slightly reflective and your baffles need to be larger and closer together than you might expect to totally exclude the light. I have to use mine in subdued light as in bright light with the tube oriented in a particular direction there is a possibility of light leakage.

I use 120ml of developer continuously agitated in a water bath and have found the process to be very straight-forward and as easy as 35mm in a standard Patterson dev tank. The total cost of the three tubes I made was £23 including a special ABS type adhesive of which I have plenty left and could probably make many more tubes.

Gary Nylander's idea looks excellent and I would probably try this first if I already had the 120 type dev tanks as the materials are probably cheaper and easier to find and would require less work to make.

**John Hannon** · 13-Jan-2006, 06:58

Here is the link I think Mark was looking for for the light trap style tubes. There is also a link to click on to see the original design.

www.btinternet.com/~g.a.patterson/photos/lfdevelop.html

**phil sweeney** · 13-Jan-2006, 10:22

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film tube construction

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**David Van Gosen** · 13-Jan-2006, 15:42

J & C sells some tubes:

www.jandcphoto.com/index.asp?PageAction=VIEWPROD&ProdID=222

They look like they were originally used for transporting rolled blueprints, so I bet they could be found cheaper through another source.

**Donald Qualls** · 13-Jan-2006, 21:29

Cheaper than that, David. They're made for carrying welding rod. You can buy the same tubes at welding supply houses, but they aren't opaque black plastic and don't have the o-rings to provide a liquid seal.

If cheap is it, go with ABS -- the ABS (cellular core) drain pipe I've seen in the United States is extremely smooth on the inside (you do *not* want stuff in a drain pipe hanging up partway along!), and as long as the mouth of the tube is smooth, the interior won't scratch. The ABS is already black and opaque, as are the caps and couplers, and the interference fit means you don't need o-rings to make liquid tight connections; just push the pieces together. And it's cheaper than PVC the same size (and comes in larger sizes). The only down side with ABS is it's not suitable for use inside a daylight tank because the cellular core tube floats, which can leave one edge of your film high and dry inside the tank; that's not an issue when the tube *is* the tank.

**Mark Tweedie** · 14-Jan-2006, 03:40

Thanks for the link John. It's not the one I found but the link within it is! However this looks clearer and easier to fathom than the original. However, my baffles are approximately the size shown in the photo and they are not light tight when spaced at 1 inch (required because of the size of the couplers - I suppose it might be possible to cut down the couplers though I doubt they could be made much less then 0.75 inches). I would make the cut-off slightly smaller on each baffle and I'm pretty sure the tube would empty in 5 or 6 seconds.

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www.btinternet.com/~g.a.patterson/photos/lfdevelop.html

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**Donald Qualls** · 14-Jan-2006, 09:53

FWIW, on my daylight fill tubes, I drilled a hole in the end cap, glued in a piece of gray conduit PVC (which is opaque, unlike the white) about two inches long (gluing PVC to ABS requires "transition cement" which is sold right next to the ABS cement and PVC cement), and then glued a disk of ABS with four cuts on the edges into the "well" of the cap (the reduced diameter portion, past the socket that fits the pipe). These tubes will fill in 4-5 seconds and drain in about half that (capacity 8 ounces for a single 4x5). For the liquid seal needed with inversion, I used a PVC cap that fits the gray pipe.