The question really is, where is the bit of mould you miss? If spores are
always in the air, it will soon re-establish itself. My guess is there is
somewhere where its really bad which you have not found or is difficult to
get at.
Brian

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"Caecilius" wrote in message
...
On Mon, 25 May 2020 08:29:01 -0700 (PDT), polygonum_on_google
wrote:

We have a small, nay, very small lean-to greenhouse.

Trouble is, we are getting quiet a lot of powdery, mildew-like, mould
inside it. It is bare treated timber.

Despite opening the doors as much as possible, it has got worse.

I have now given it a good scrub and the sun is drying it out. But I would
like to do something to stop it happening again and again. Any
suggestions? My suggestions so far have not gone down well. :-(

I've found benzalkonium chloride works well for moss, algae and mold.
It's what's used in a lot of patio cleaners, but it's a lot less
expensive to buy it in more concentrated form as "BAC 50".