Kodak Hypo Clear - mixing???

[Matt5791]

I have bought a bag of Kodak Hypo clearing agent.

I have never used this before but I am really stuck on how to mix it up. On the bag it says something about stock solution etc etc.

Am I right in thinking that you mix a concentrated solution and then use this to make a dilute useable solution?

Any help would be very gratefully received.

Many thanks,
Matt

 

[Gay Larson]

that's what I do, mix a stock solution and then dilute as needed.

 

[Matt5791]

WHat is the mix for the stock solution though? - it doesn't seem to say anywhere on the packet.

Thanks,
Matt

 

[Gay Larson]

I think it is two ounces per gallon of water, I put about two ounces in a tray of water. I'm not sure of the exact amount but it works for me. someone else might have a more accurate mixture. I know it's not a lot for a gallon of water though.

 

[Tom Hoskinson]

WHat is the mix for the stock solution though? - it doesn't seem to say anywhere on the packet.

Thanks,
Matt

Kodak list a 5 gallon size packet of dry chemicals and a 1 gallon size packet.

The 5 gallon packet is apparently intended to produce 5 gallons of concentrated HCA. Each gallon (or fraction thereof) of concentrated HCA is then further diluted 4:1 with water to produce 4 gallons of HCA working solution.

The 1 gallon packet is apparently intended to produce 1 gallon of concentrated HCA. This concentrated gallon (or fraction thereof) of concentrated HCA is then further diluted 4:1 with water

Is the weight of the packet listed? If not, can you weigh your packet and post the result?

Since I know that the primary ingredient in Kodak HCA is Sodium Sulfite (about 20- 25 grams Sodium Sulfite per liter of working solution) I can figure out if you have the 1 gallon or the 5 gallon size.

Other Kodak HCA ingredients are probably:

Sodium Metabisulfite (Sodium Sulfite Buffer)
EDTA Tetrasodium Salt (Sequestrant/water softener)
Sodium Citrate (5,5-hydrate) (Sequestrant/water softener)

 

[FrankB]

I've been mixing it from the powder as required and then resealing the yellow bag with tape. I worked out the concentration by dividing the working strength volume by the weight of the contents (litres and grams to keep things simple, figures given on the side of the bag).

I think it worked out at 24g per litre of water. I'm not sure whether this is right or not, but it seems to work okay.

 

[msage]

Matt
Yes, the easest way is to mix a stock solution and then dilute for a working solution. I use the 5 gallon package. Mix the powder in water to make one gallon to make the stock solution. Then mix one part of the stock solution with four parts of water(1:4).

 

[Michel Hardy-Vallée]

Actually the recent Kodak packages of Hypo-Clearing agent also come in 1 Liter packages, at least in Canada! The packaging states clearly what volume of water you should dilute the powder into, and then what at dilution you should use that solution. Isn't it on your package? Is it shiny plastic yellow, or matte paper/plastic packaging?

 

[Tom Hoskinson]

One of Matt's problems is that he does not know what size HCA packet he has. ("WHat is the mix for the stock solution though? - it doesn't seem to say anywhere on the packet.")

I advised him to weigh the packet. See my previous post in this thread.

 

[FrankB]

I've done the sums based on my supply. If Matt mixes 24g of HCA powder per litre of water he will end up with a working strength solution, regardless of size of his packet.

Ahem, I could have put that better really! I'll get my coat...

 

[dolande]

I have a package market as 125g, 4.4oz and is good for 950ml (0.25 US gallon) stock and/or 4.73 (1.25 US gallons) working solution.
Rafael

 

[Tom Hoskinson]

I've done the sums based on my supply. If Matt mixes 24g of HCA powder per litre of water he will end up with a working strength solution, regardless of size of his packet.

Ahem, I could have put that better really! I'll get my coat...

Close enough for govenment work, Frank!

 

[FrankB]

My public reason is these pesky d****** scales only read out in 2g increments.

I could tell you the real reason...

...but then I'd have to kill you!

 

[Dave Miller]

It doesn’t necessarily apply in this instance, but there is always a danger with dry chemicals that they are not mixed consistently in the bag, or that they have separated since packaging. Therefore when a portion is selected, as here, the consistency of the mix can be uneven, and cause problems.
Much better to mix the entire contents as recommended, and store the stock solution for future use.

 

[FrankB]

Fair point, Dave. I hadn't thought of that.

Oh well, looks like I have a use for all those old storage bottles after all!

 

[Mike Kennedy]

I must concur with Dave Miller. (Mix the entire amount of dry chemicals)
When I first started to develop B&W film my idea was to make small amounts (1 liter) from huge packages of dry chemicals that I purchased at a local auction. My "old school" mentor pointed out that these bags held a variety of compounds , each having a different weight. You could never be sure of consistency from one batch to the other.

Mike

 

[Matt5791]

OK - on examining the bag more closely it carries instructions of making a stock solution or a working solution - the whole contents makes 3.8L / 1 US gallon Stock OR 5 US gallon working. I guess I make a stock and store - although I need some more containers and I need to use it tonight so I may go with Franks's idea now and make a stock solution later.

Thanks for the very helpful posts.

Matt

 

[FrankB]

In light of other posts, I'd give the bag a damn good shake before using my (less than brilliant, as it turns out!) suggestion!

All the best,

Frank

 

[dancqu]

In light of other posts, I'd give the bag
a damn good shake

Prospectors call that Jigging. Jigging is used
to Separate the constituents of a mixture. Now
you wouldn't want to do that would you?

From the kitchen find a mixing bowl. Pour in all
the mix then Fold and Stir. Dan

 

[FrankB]

<sigh> I'm not having a good day.

Dan, I agree that your method is probably better (and from now on I'm going back to liquid chems where I belong). I would however suggest that it is possible to combine powdered ingredients of differing densities, to some extent, by means of violent agitation (a.k.a. "a damn good shake") in a sealed container without contaminating other vessels.

However, to complete your recommendation, I would also suggest that after implementing your method the bowl should not be returned to the kitchen but should be "acquired" for darkroom use only...

 

[dancqu]

... I would also suggest that after implementing
your method the bowl should not be returned
to the kitchen but should be "acquired" for
darkroom use only...

I consider safe the chemistry in general use. Perhaps
I know how to handle it safely. Also, I trust myself in
selecting gear and location when preparing.

Dust masks, gloves, and tongs were unheard of and
unseen by myself when I got into darkroom work
many years ago. I've still no use for them.

All the cautions, warnings, and dangers pronounced
surrounding darkroom work, IMO, dissuade those that
might otherwise be participants. Dan

 

[Mike-D]

Easiest clearing agent for me is a tablespoon ~ 25g of sodium sulfite in a liter of water. Pretty much approximates the working solution strength (20g/Liter).

Mike D

 

[Gerald Koch]

My public reason is these pesky d****** scales only read out in 2g increments.

Depends. I have a digital postal scale that reads in 1 gram increments.