Ilford Washaid is a hypo clearing agent (HCA) supplied as a liquid concentrate for dilution 1:4 for use.
Whilst Kodak Hypo Clearing Agent is the industry standard, some photographers prefer the convenience of working with a liquid concentrate. HCA is almost essential when washing fibre based papers, but it is also highly desirable when washing film as it can greatly speed up the wash sequence, save a lot of time and water and ensure the film is thoroughly purged of residual fixer.
As a basic rule of thumb, when washing film, give an initial rinse after fixing – a couple of tank changes of water at 18–24ºC. Then fill the tank with Hypo Clearing Agent, at roughly 18–24ºC, and agitate continuously for around 2 minutes. Pour out the solution and then give a further 3 or 4 water changes, and in the final one add some wetting agent to the tank (use distilled water for this final tank full if you are in a hard water area).
It is essential to wash film and paper correctly as leaving any fixer residue will significantly jeopardise its lifespan.
Note: the colder your wash temperature the slower it is. If washing at cold tap temperature, which is around 10ºC depending on time of year and your supply, wash times would be very long and extremely inefficient. Ansel Adams explores this in detail in his book “The Print”. Wash temperature should not fall below 18ºC as efficiency falls away very quickly below this.