Baffling . . . stuffing . . .

Folks:

I am in the process of sealing up a plenum project. So far all has
gone well using regular baffle seal and silicone P strip.

However there are several places of extremely irregular shape that I
cannot seal with the baffle seal or P strip. Some of the guys around
my field have advised that the tricks of the trade are to stuff the
tough spots with either dry fiberglass cloth or steel wool.

I am not thrilled with either trick, although I concede that they
would work.

The dry glass cloth is going to be difficult to secure in place and
frankly would look like a bunch of rags stuffed into the crevices of
an otherwise nice installation. The steel wool is, well, steel wool.
In no time it is going to be corroded and nasty and it is obviously a
bit on the abrasive side. And I don't think it would seal very well,
to boot.

So I'm looking for suggestions of something I can stuff into an oddly
shaped hole in contact with the cooling fins on an engine. I like the
idea of silicone foam as it will take the heat and it's very
conformable, but before I spend the big bucks I thought I would cast a
wider net to see if there is a simple trick that I have not thought
of.

Thanks in advance and take care--

Steve.