I totally understand your thinking behind the whole 'use detergent to wash hands and not just water' scenario and in certain circumstances, I agree there is a need for the use of chemicals.
I too use chemicals, when all other options have been examined.
However, to justify the use of chemicals to clean drives that could be cleaned perfectly well using just water (and in my opinion just as well as with chemicals) by stating that it creates less wear on the blocks is not a well thought out argument.
The long term damage of pressure washing to the blocks is neglegible, especially if the operator is experienced. However the long term damage to the customers land/soil/garden whatever you want to call it by the use of chemicals is more than likely to be quite significant.
I don't want to get into an in depth discussion about this and was just asking the question originally to see if there was some trade secret that had evaded me for all this time... it appears not.
If that is the method you wish to use then of course I have to respect that and know that your results are excellent Roger as can be seen on your website, however, if there is anyone reading this who is wondering which course to take, then I just ask that you think of the damaging effects of chemicals on the environment before pursuing that particular avenue.
Please do not get me wrong (as so often happend to people in this forum), I am not picking an argument with anyone here, I am simply expressing my opinions on a subject I feel strongly about.
Roger is very giving of his knowledge and I have respect for him and his business.