Avoiding "blix burp"

rbultman · Jan 24, 2016

I developed my first roll of Portra 400 yesterday using the Unicolor 1L powder kit. I poured out the developer and then poured in the blix. I quickly placed the lid on the Paterson tank and started the initial 10 inversions. After a couple of inversions, the top began to bulge such that I thought it might pop off. I set the tank down, lifted the lid at one place in order to allow the gasses to escape, and blix shot out onto my work surface. How can I keep the mess from happening? Should I use the swizzle stick initially, giving this out-gassing some time to occur, and then do some inversions?

Regards,
Rob

Rick A · Jan 24, 2016

Aren't you supposed to do a water rinse between steps? It's been years since I've run any color, I don't recollect ever having that issue.

zehner21 · Jan 24, 2016

Use a stop bath. I've never experienced "bleach/blix burp"

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rbultman · Jan 24, 2016

Rick A said:
Aren't you supposed to do a water rinse between steps? It's been years since I've run any color, I don't recollect ever having that issue.

Not per the Unicolor data sheet. It only calls for a wash between blix and stab.

rbultman · Jan 24, 2016

zehner21 said:
Use a stop bath. I've never experienced "bleach/blix burp"

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Do you use just a standard B&W stop or is there one specific to C-41?

zehner21 · Jan 24, 2016

Avoiding "blix burp"

rbultman said:
Do you use just a standard B&W stop or is there one specific to C-41?

Photo Engineer suggests an acetic acid based stop bath.

markbarendt · Jan 24, 2016

Surprised me the first time too.

It is a normal part of the chemical reaction for the bleach to off gas, the tank needs to be burped. When using hand tanks removing the fill cap between inversions does the job.

rbultman · Jan 24, 2016

markbarendt said:
Surprised me the first time too.

It is a normal part of the chemical reaction for the bleach to off gas, the tank needs to be burped. When using hand tanks removing the fill cap between inversions does the job.

Thanks, Mark.

Rudeofus · Jan 24, 2016

markbarendt said:
Surprised me the first time too.

It is a normal part of the chemical reaction for the bleach to off gas, the tank needs to be burped. When using hand tanks removing the fill cap between inversions does the job.

The "burps" appear because C-41 CD contains lots of carbonate, and the carry over CD releases Carbon Dioxide when it gets in contact with the slightly acidic BLIX. Pretty much the same would happen with an acidic stop bath, and the more carry over CD is left in the tank, the stronger the burps will be.

If the burps become too annoying, I recommend a very brief water rinse between CD and BLIX, basically just fill with water, invert once, pour out, enter BLIX. This should remove most of the carry over carbonate and resolve the burping issue for good.

Another method would be to leave the tank lid open right after BLIX is poured in, and agitate in a way which avoids inverting the film tank. After a minute all excess Carbon Dioxide should have escaped, and you can put the lid in place, and the process can then continue normally.

Photo Engineer · Jan 24, 2016

Sorry, but I cannot support the use of any water rinse after the CD. There will be too much development taking place even with the rinse. Use a stop and get the burp or don't use one and just get a blix burp. This is more pronounce if the maker of the kit uses more carbonate and / or a more acidic blix to get more activity.

I have never had this problem with Kodak chemistry.

PE

Rudeofus · Jan 24, 2016

Photo Engineer said:
Sorry, but I cannot support the use of any water rinse after the CD. There will be too much development taking place even with the rinse.

A water rinse dilutes the CD by at least a factor of 25, so development should be very slow. with some practice, this water rinse should take no longer than 20 seconds, which makes dev action comparable to one second of extra development in full strength CD.

Photo Engineer said:
Use a stop and get the burp or don't use one and just get a blix burp.

Nobody would be worried about a small burp, but Rob wrote that BLIX splashed all over the place, which is a problem IMHO. Fortunately BLIX is mostly benign despite its scary name and color.

Photo Engineer said:
This is more pronounce if the maker of the kit uses more carbonate and / or a more acidic blix to get more activity.

BLIX should be near neutral, since it's the last concentrated liquid to touch the film ---> pH should be close to 6.5. Either this particular kit's CD is loaded with carbonate, or Rob has excessive liquid carry over in his process chain.

rbultman · Jan 24, 2016

I start draining the tank 15 seconds before the end if the dev time period to ensure I have a sufficiently drained the tank. Given that it was my first roll, I was a little nervous and may not have drained as much as I normally do with black and white.

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Arctic amateur · Jan 25, 2016

How about CD - stop - water - blix? That's what I usually do.

My stop is citric acid, is that a bad idea?

Rudeofus · Jan 25, 2016

Arctic amateur said:
How about CD - stop - water - blix? That's what I usually do.

If BLIX causes carry over CD to burp, then an acidic stop bath will cause even stronger burps. While "stop bath burps" and resulting splashes will be less colorful than "BLIX burps", they are not better.

Arctic amateur said:
My stop is citric acid, is that a bad idea?

Can't say for sure. There exists some Kodak PDF document in which a mixture of Citric Acid and Rapid Fixer is recommended for removing the orange mask from B&W developed C-41 film. This statement can be construed as "Citric Acid plus Thiosulfate will destroy color dyes in C-41 film", which would mean that one should avoid Citric Acid in color processing altogether. At the same time there are many folks who use Citric Acid as stop bath in color processing and nobody has reported problems so far. None of these folks have made densitometric tests either, so the absence of problem reports does not necessarily imply lack of problems. YMMV.

mrred · Jan 25, 2016

I had it happen once. That was enough for me and the solution was easy.....don't put the cap on during blix. Swish and don't invert. I moved on.

Arctic amateur · Jan 25, 2016

Rudeofus said:
If BLIX causes carry over CD to burp, then an acidic stop bath will cause even stronger burps. While "stop bath burps" and resulting splashes will be less colorful than "BLIX burps", they are not better.

Hence the water wash between stop and blix.

Rudeofus · Jan 25, 2016

Arctic amateur said:
Hence the water wash between stop and blix.

The problem is not interaction between acidic liquid and BLIX, it's between color developer and whichever acidic bath would follow, in your case it's the stop bath.

Arctic amateur · Jan 25, 2016

Thank you. I misunderstood earlier.

rbultman · Jan 25, 2016

mrred said:
I had it happen once. That was enough for me and the solution was easy.....don't put the cap on during blix. Swish and don't invert. I moved on.

Just to be pedantic, you do no inversions whatsoever with blix as opposed to just the initial inversion period?

Regards,
Rob

KidA · Jan 25, 2016

Do you have a Paterson tank? Or something similar which has a 'soft' lid? Every time I agitate (using inversions) I place the tank down and with one hand lift an edge of the lid to create a small opening for air to run freely out and push down in the middle of the lid with my other hand. While still pushing down, I close the small, open part of the lid again. You can even do this without lifting one side of the lid, but it creates unnecessary pressure on the lid and you run the risk of breaking the lid, I've seen it happen! This creates negative air pressure that allows for a) a better seal, as sometimes chemicals can drip and b) allows for any small amounts of pressure build-up or burping.

Avoiding "blix burp"

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