Hi John.
Heavy, old blood stains on carpets can some times be 'crusty'. Careful use of a stiff brush, such as a velvet boffin, followed by a dry vacuum can remove the upper layer.
Next, a cold water rinse. With a CFR hand tool it can be held almost stationary over the stain, which not only flushes some out but also partially re-hydrates the blood.
The choice of spotter is mainly between enzyme or ammonia-based (eg. B144 Stainpro), or in the old days before CC chems were available I would use cloudy ammonia.
My favoured product is B144, applied by repeated dabbing with a towel, followed by a cold rinse. Then the rust remover and a final rinse.
So your choice of chemicals coincides with mine, the only difference is maybe the method of application. Using the towel rather than direct application reduces the possibility of wick-back and also gives you an indication when to start with the rust remover (when there is no further transfer to the towel).
Rust removers based on Hydrofluoric acid have an almost indefinite shelf-life.
If the above proceedure fails to remove all the staining then the last resort it ammonia-boosted peroxide which can remove the greenish afterstain, but must only be used with great care.
John.
