Is this alkali/neutral/acid fixer?

[baachitraka]

https://www.fotoimpex.de/shop/syste...arzweiss Fixierer & Stoppbad&artnr=963000&pn=

 

[miha]

Acid. pH 4,6.

 

[baachitraka]

That is quite acidic indeed compared to their liquid fixer.

 

[MartinP]

The material is fully described in the information sheets at the link given by the OP. Is there a specific reason for thinking the information is wrong?

 

[idamia]

It's the standard sodium thiosulfate + sodium metabisulfite fixer.
Metabisulfite (= disulfite, S2O52-) in hydrolized in water to give hydrogen sulfite (HSO3-), which is an acidic anion.

 

[Gerald C Koch]

It's the standard sodium thiosulfate + sodium metabisulfite fixer.
Metabisulfite (= disulfite, S2O52-) in hydrolized in water to give hydrogen sulfite (HSO3-), which is an acidic anion.

A pH of 4.6 is not very acidic. Very acidic woud be a pH < 1. At 4.6 you're near the acidity of tomato juice.

 

[Rudeofus]

A pH of 4.6 is not very acidic. Very acidic woud be a pH < 1. At 4.6 you're near the acidity of tomato juice.

Most rapid fixers today are somewhere around pH 5.5, and the most advanced ones are at pH 6.5. Therefore, for a fixer, pH 4.6 is quite acidic, especially if you consider that fixers turn more acidic over time, and that Thiosulfate disintegrates as pH goes below 4.

 

[baachitraka]

Will drop in pH accelerates fixing times?

 

[idamia]

A pH of 4.6 is not very acidic. Very acidic woud be a pH < 1. At 4.6 you're near the acidity of tomato juice.

This is because hydrogensulfite is a quite weak acid with an pKs of 7.