[chris scott]

No Problem.

[clarkson]

That's a complete misconception. Brian Crowe in the late 80's did a very good job of "educating " conservation groups on this new superheated way of cleaning things. It is still specified today...he did a good job. He also created himself a very niche market. Today it the "doff" is bought by the uneducated to clean drives, walls etc. It's most prevalent recent use is the cleaning of render....although K rend state a maximum of 60 centigrade only. Again sales are based on a niche market.

Saying the Doff sterilises the surface is true... albeit shortlived. These microorganisms are air bourne and will grow and multiply given the right conditions. The doff does nothing to address the environment in which they grow, so they will come back.

"Adjust" the environment and the use of a biodegradable biocide will give better long-term results. Whilst not biodegradable bleach would work ,but the mechanism by which it works is not ideal when metal window frames and the likes are present.
The Yanks like to shout about it's use but a) it aint biodegradable and b) it; highly corrosive
I have two DOFF machines and I was "trained " at Stonehealth  15 years ago

hi chris
i have always agreed with your above  comments. if heat is needed you can use a small machine into a mazzoni for very similar effect. at a fraction of the price.

cheers
john