Nice job Ash. I bet you had a quick sniff of those knickers
Not sure if it's a different level of sunlight or something but the carpet actually looks a completely different colour after cleaning!!
Russ it's much more efficient, quicker and uses no more product when you feed a rinse chemical through your machine in the normal way
If you spray it on top before extracting it's not getting in to contact with the carpet fibres properly, so would be pretty useless... unless you really doused the carpet, in which case using MORE product, taking much longer and getting the carpet wetter!
For the purpose of neutralising with acidity I rarely use the recommended dose in the chemical feed, much weaker usually, because the high volume of water flushed through by the TM leaves very little neutralising to do.