Prewash on older machines.
Launderess, as you may know many vintage machines like the AEG in question were based on earlier machines, when biological detergents were not a thing.
But starting from the late 60s early 70s you started to see enzymes being implemented in detergents
Before "complete" detergents you had enzymatic presoaks to do a separate procedure eventually.
AEG machines, I mean the real actual AEG's (not Zanussi) such as Clara, Regina, Bella and so forth were still based on machines of old that actually relied more on temperatures hence oxygen (perborate) in detergents, many house makers still relied in a good oxygen laden "kochwäsche" rather than those fancy modern enzymes, those machines have a multiple series of elements pulling 3kwh, my claras both Clara of the 70s and the later Clara SL would heat water to 90°c in a matter of 20-25 minutes tops, and the actual main wash progress mostly at the hot temperature, and pretty quickly, they start heating and just progress.
That is if non bio button is activated.
If activated, the bio button exclude one series of elements until it reaches the program number 3 IIRC, meaning that you get an actual slow increment in temperature and a pretty long enzymatic phase, until a certain point when it starts using all the elements and reaches the desired temperature.
The BIO button started being included only from late 60s.
Other machines like my Zerowatt instead had a very long prewash. A Bio prewash.
Others like Candy SA98 had an automatic biological soak as part of the wash, it could be timed up to 12hrs, she would start and heat to 45°c and then based on how much soak time you set she would stay on soak and then proceeded with the wash.
That is how the prewash became just a thing to remove the biggest soil, but all the action now shifted to the main wash only.
AEG though were very versatile, they would adapt to every washing habit.
Pre wash in AEG was always very brief, beside the bio button AEG such as those we are talking about also had a separate soak program. They would fill at a very high level, they would heat water to 40 tumble for awhile and then just stay there, until you put in on spin and proceed with the desired program
That gave whoever was charged with the laundry total freedom of doing things the way they wished.
You could get a eparate presoak and proceed with the normal fast heating boilwash.
You could do just a brief prewash and go on with the fast heating boilwash.
Or use a product like Ariel and do just one main wash with an enzyme phase by pressing the bio button.
Very versatile machines
