Is Ilford Rapid fixer an acidic fixer or alkaline fixer?

Doremus Scudder

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The following is from Ilford's tech pub on Rapid Fixer (readily findable with Google if you want the rest).

"pH and specific gravity
The following table gives the pH and specific gravity (SG) for fresh, working strength ILFORD RAPID FIXER. These figures were obtained under carefully controlled laboratory conditions and may differ slightly from measurements made by users in their own working areas. Users should make their own control measurements from their own
accurately mixed fresh solutions for later comparison. Ideally a pH meter should be used to measure solution pH but if one is not available pH measurement sticks can be used. These are available in various pH ranges and those covering
a range from pH 4 to pH 6 are sufficient. SG can be measured by using a hydrometer and one covering the range from 1.000 to 1.200 is useful for a wide range of photographic process solutions.
dilution..........pH..........SG at 20ºC/68ºF
...1+4............5.0–5.5.........1.070–1.080
...1+9............5.0–5.5.........1.030–1.040"

Doremus
 

mshchem

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Ilford rapid fix is acidic, however it is not like the older "acid hardening" fixers used when film emulsions were soft and fiber base papers were dried on big drum driers.

Kodak still includes the option of a hardener, added separately for rapid fix. Also most powdered fixers have a boric acid and alum component that is hardening.
 

mshchem

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OLD SCHOOL POWDERED FIXER. STILL SOLD TODAY. BEEN AROUND FOR EVER. MISERABLE STINKY STUFF.


KODAK ACID HARDENING FIXING BATH F-5

600 ml Water (125F or 45C)
240 g Sodium Thiosulfate
15 g Sodium Sulfite
48 ml Acetic Acid (28%)
7.5 g Boric Acid (Crystals)
15 g Potassium Alum
Top up to one litre water

Fixing Time: Twice the time it takes to clear a plate, usually 2 to 4 minutes.

Temperature: 20C Agitation: Intermittent

Shelf life: This stock solution lasts practically indefinitely, dump it when it starts to take longer than 5 minutes to clear a plate

Source: Photo Lab Index, Lifetime Edition, Morgan and Morgan, Inc., Dobbs Ferry, New York.
 

Rudeofus

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There are two types of "acidic fixers":

  1. pH <= 4.8: these are quite acidic and allow use of alum based hardeners
  2. 4.8 < pH <= 5.5: these are acidic enough such that you won't need a stop bath, but you can't use alum based hardeners
As several others have already pointed out, Ilford's Rapid Fixer products fit into category 2.
 

koraks

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That was my first thought: perhaps they want to use a staining developer. Which I've done a lot, and more often than not with acid fixers. Works fine. I know several others do this too.
 

MattKing

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The OP is fairly new to all this, and may have read some of the recommendations for neutral fixer when it comes to issues like wash times.
I would respond to that by saying that Ilford Rapid Fixer is only moderately acidic, so the advantages of neutral fixer over it aren't large, and its cost and availability argue for it.
 
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