Sodium Metasilicate as a developer

[picbits]

I've just looked in the boot of my car and discovered a 25Kg sack of pure Sodium Metasilicate Anhydrous

I've been using the Sodium Metasilicate developer crystals for developing photo boards for a number of years but have always bought them in small packets of 50g each (diluted with .5 to .75L of hot water).

I understand the stuff sold in the small packets is Sodium Metasilicate Pentahydrate but does anyone know if the straight Sodium Metasillicate (not Pentahydrate) is any good for developing before I crack open this large sack ?

Typically I'd bought 10 packs of 50g developing crystals at around £1 each before I "discovered" this sack of stuff on my journeys

 

[jpanhalt]

Yes, the chemistry is the same. See:Sodium silicate - Wikipedia, the free encyclopedia

If using the anhydrous form, you must make adjustment for the change in formula weight (FW). The FW for the pentahydrate is 212.14, and for the anhydrous form, it is 122.06. Thus, if you were using 100 g of the pentahydrate, you would only need 57.5 g of the anhydrous form (i.e., 122/212 X 100g).

Note, the rate of solution of the hydrate and anhydrous forms may be quite different (I don't know, because I buy it as a 40% solution). You may want to just make a similar concentrated solution and use that.

John

 

[picbits]

Sounds like good news to me Definitely worth missing out on lunch for a free sack of the stuff lol.

I'll probably just end up putting it next to my (unopened) 25kg sack of Sodium Persulpate for a couple of years though lmao