billtroop
Member
- Joined
- Aug 28, 2005
- Messages
- 134
- Format
- Multi Format
>I'll tell you how decimals get added.
Ron, of course you're right - - but the additional amounts - - potentially as much as 5-10% as Haist told me - - are seldom if ever reflected in the published formula. These amounts are for manufacturing only. Furthermore, such amounts will usually be greater, not lesser. In the incorrect D-61a we have more metol, but less HQ. Hence, it is unlikely to be a manufacturing variant.
Re D-61a, ask yourself why and for whom the formula was published?
>In the UK Kodak sold "Kodak" Sodium Carbonate as the anhydrous form I have a 1950's Tin ?3.5Kg in my chemical store.
Ian, you could buy anhydrous, of course, but monohydrate was preferred at any point that it was economical to use, because it is so much more stable. Published formulas from EK (in the US) typically use the monohydrate because there is the expectation that there may be lengthy storage of the chemical before mixing. The monohydrate is always more expensive and at present, even in the US, is quite a bit more expensive, so I expect to see its use decline. As far as I know, the least expensive source of monohydrate available in the US at present is not manufactured in the US, an additional factor to consider.
If I recall correctly, later Ansco formularies also specify the monohydrate, for the same reasons.
Ron, Ian - - have a look at the publications introducing D-25. These make clear what has always been an overriding concern for Kodak as regards any published formula: it must be easy to use, and must be proof against coarse measurement technique, including sub-lab-quality scales. This is why they seldom if ever have fractional gram amounts except for chemicals, such as KBr, where there is the expectation that, for accuracy, a 10% solution will be used.
It is abundantly clear that Kodak did not expect anyone using their published formulas to have equipment capable of measuring fractions of a gram accurately. It is buncombe to suggest otherwise.
Has anyone looked at the equipment section of PCS? Or similar in contemporaneous publications?
Shucks, it's hard enough today to find a cheap scale with reliable measuring of a tenth of a gram! (which dictates resolution to at least a hundreth of a gram)
Kodak was above all a practical company.
Ron, of course you're right - - but the additional amounts - - potentially as much as 5-10% as Haist told me - - are seldom if ever reflected in the published formula. These amounts are for manufacturing only. Furthermore, such amounts will usually be greater, not lesser. In the incorrect D-61a we have more metol, but less HQ. Hence, it is unlikely to be a manufacturing variant.
Re D-61a, ask yourself why and for whom the formula was published?
>In the UK Kodak sold "Kodak" Sodium Carbonate as the anhydrous form I have a 1950's Tin ?3.5Kg in my chemical store.
Ian, you could buy anhydrous, of course, but monohydrate was preferred at any point that it was economical to use, because it is so much more stable. Published formulas from EK (in the US) typically use the monohydrate because there is the expectation that there may be lengthy storage of the chemical before mixing. The monohydrate is always more expensive and at present, even in the US, is quite a bit more expensive, so I expect to see its use decline. As far as I know, the least expensive source of monohydrate available in the US at present is not manufactured in the US, an additional factor to consider.
If I recall correctly, later Ansco formularies also specify the monohydrate, for the same reasons.
Ron, Ian - - have a look at the publications introducing D-25. These make clear what has always been an overriding concern for Kodak as regards any published formula: it must be easy to use, and must be proof against coarse measurement technique, including sub-lab-quality scales. This is why they seldom if ever have fractional gram amounts except for chemicals, such as KBr, where there is the expectation that, for accuracy, a 10% solution will be used.
It is abundantly clear that Kodak did not expect anyone using their published formulas to have equipment capable of measuring fractions of a gram accurately. It is buncombe to suggest otherwise.
Has anyone looked at the equipment section of PCS? Or similar in contemporaneous publications?
Shucks, it's hard enough today to find a cheap scale with reliable measuring of a tenth of a gram! (which dictates resolution to at least a hundreth of a gram)
Kodak was above all a practical company.