[Cob] Plaster Mildew

[michael montagne]

The rains have started here in Portland.  I re-plastered my oven this summer
with a clay/sand plaster.  There are now several spots of mildew that appear
and only go away when it gets hot and dry.  Since it won't be hot and dry
for many months, I'd like to see about getting rid of the mildew.  I've
heard of incorporating borax in the plaster mix to help prevent this sort of
thing.  I tried a borax/water wash that didn't seem to help, at least
immediately.

-mjm