Microphen Matters.

[calebk]

Hi guys, I bought my second batch of Microphen this evening to make more stock solution but I've still got some stock solution left from about a month ago.

Just wondering if it'd do my new batch any harm to mix it with the old batch once the new batch is prepared and cooled.

The old batch was stored in airtight but not light tight containers, but there is air present in the container so I think the old batch might have oxidized a little.

 

[tlitody]

if you have enough old for next film dev then don't mix em. there's simply no need. And don't mix new stock from powder until 24hours before you need it.
I think old stuff will work fine if its only a month old. The degree of straw colour will indicate how much oxidation has taken place. If there's only a hint it'll be fine but if it has turned yellow to brown then toss it.

 

[taylan]

If you are working with zone system do not mix but if you aren't, i think you won't notice the differences in your results. You can mix it.
BTW If i were you i did not mix.

 

[Roger Hicks]

If you are working with zone system do not mix but if you aren't, i think you won't notice the differences in your results. You can mix it.
BTW If i were you i did not mix.

Why would the Zone System make a difference?

To the OP:

If the existing stock is still good (water clear, or only very pale yellow), I might use all of that, topped up with the new stuff, to make whatever volume of 1+1 or 1+3 you need, but re-using stock with extended dev times makes a mockery of the Zone System. You need either one-shot or fully replenished for consistent development.

Mixing old stock and new will probably shorten the life of the new solution -- I think the oxidation and hydrolysis reactions are autocatalytic -- but Marty will know better than I about this.

I am, however, reasonably sure that some of the hydrolysis by-products of Phenidone are colourless, so some very old PQ devs (a year, rather than a month, and even then, not all devs) may be dead even when they're clear.

Cheers,

R.

 

[tlitody]

I use those black concertina bottles to store dev so I can remove nearly all air before storing for next use. I store in my fridge. So life of stock is quite long if not used for a while. And I never had one of those concertina bottles which unconcertined during storage so I don't think they let air through or if they do it is a tiny amount.

 

[calebk]

I use those black concertina bottles to store dev so I can remove nearly all air before storing for next use. I store in my fridge. So life of stock is quite long if not used for a while. And I never had one of those concertina bottles which unconcertined during storage so I don't think they let air through or if they do it is a tiny amount.

Are these like accordion bottles or something? I think the film supplies shop here sells them but they're out of stock at the moment.

 

[Roger Hicks]

Are these like accordion bottles or something? I think the film supplies shop here sells them but they're out of stock at the moment.

According to all the developer manufacturers I've spoken to, these bottles are surprisingly oxygen-permeable and often offer less protection than glass. Optimum is full brown glass bottles; after that brown glass + Protectan.

I have never verified this permeability but I see no reason why the manufacturers would lie.

Cheers,

R.

 

[tlitody]

Are these like accordion bottles or something? I think the film supplies shop here sells them but they're out of stock at the moment.

Yes they are the accordian style bottles. Manufacturers use plastic bottles which work very well for long term storage of their chemicals. I've never had problems with them. Colour of bottle is irrelevant if its stored in a cupboard or fridge out of light not that I think light is an issue anyway unless you are keeping bottles in direct sunlight. A litre of microphen stock is going to be used pretty quick anyway and the water you mix it with contains more oxygen than any miniscule amounts that might seep in through plastic. Chemicals react with water so no matter how airtight or light tight your bottles, it will go off after a period of time anyway. i.e. worrying about air permeability is an old wives tale. It's just not something you need to worry about. The tiny air gap at the top of the bottle will contain many times more oxygen than will ever seep through the walls of a bottle. It's an argument proposed by sheep worriers.