How can I prevent fresh blix from popping the Patterson tank lid?

[Samu]

There is one more solution for this problem: Do not use the "new" Paterson tank for developing color film. There are better options for this, I personally use JOBO tanks, but the "old" version of Paterson (made under various brands, as the patent has expired) is much better than those Paterson sells today.

 

[BMbikerider]

This was a problem for me but no more. When using a JOBO 35mm or 120 tank with the recommended level of developer etc the internal level does not come above the centre point on the cap . I use a .5mm drill to pierce the top of the tank and that is a vent for the gasses that can build up the hole is so small no liquid can escape in a quantity that can affect the development process.

I also have a JOBO model 4312 tank designed to take 2 x 35mm reels. The black plastic top which is screwed onto the tank base not held in place by the breakable clip devices on the newer tanks, has the usual push on red cap to allow filling/emptying the contents. This has a hole approx 3mm in diameter molded into the lid and that has never leaked. This is what gave me the idea of drilling the caps on the newer 35mm tanks.

 

[koraks]

I use a .5mm drill to pierce the top of the tank and that is a vent for the gasses that can build up the hole is so small no liquid can escape in a quantity that can affect the development process.

So now your tank leaks all the time instead of only if you forget to burp it once or twice in the one bath that follows development.

 

[BMbikerider]

So now your tank leaks all the time instead of only if you forget to burp it once or twice in the one bath that follows development.

Read the full post! (properly)

The level does not reach either the self made hole in the red cap of the 35mm tank when the tank is on its side on the Jobo processor, or the one on the older screw top cap which can be used for 2 x 35mm or 1 x 120 film. The hole is also too small to leak if the tanks were to be completely inverted because the the surface tension prevents it from leaking unless deliberately shaken when inverted. Very much the same principal as a bottle of salad dressing which also has a small hole for the condiment to be sprinkled on your food.

It will allow any build up of gases to escape naturally, but not the heavier water/developer/bleach. If it didn't work why did JOBO create one for one type of their developing tanks with a hole which is 6 times as wide? You can test this yourself quite simply with an empty screw top jar which does not leak, and a little less than half full of water with the jar on its side. Make a small hole on the top around .5mm, wide dead centre of the lid, invert the jar and it will not leak unless it is shaken.

It is very very basic science that I was taught when I was around 11 yrs old. It worked then in the Science Lab and still works today. It can be made to leak by shaking it when it is upside down. That can be over ridden but as I do not normally shake a JOBO tank that is going to be used for rotary processing that never happens.

Bear in mind for rotary processing, the amount of developer etc needed, is a little less than half that needed for inversion development and that is printed on the side of the tank!