On Fri, 20 Apr 2007 11:47:22 GMT, Stuart Noble
wrote:

Anna wrote:
On Thu, 19 Apr 2007 22:03:52 GMT, Stuart Noble
wrote:

wrote:
On 19 Apr, 12:22, Stuart Noble
wrote:

You otoh make a life of it. The level of ignorance in your comments
about putty flexibility left me gobsmacked.
I said that dried putty has zero flexibility. If you can stop it drying
by regular painting, that's another matter but, unless you want to be up
a ladder every couple of years, acrylics are a better bet.
There is currently a real shortage of materials in the known universe
with zero flexibility. Putty will bend as much as the wood frame does,
ie very slightly. The fact you can snap it does not change this.
Dried putty does not "bend", not even slightly. Wood does, often a lot
more than slightly. The two materials are fundamentally incompatible,
but I guess a conservationist wouldn't see that

I suspect that putty was designed to be painted with linseed oil paint
which kept it from drying out completely. And that since linseed oil
paints were replaced by mineral oil paints about 50 years ago putty
has not been nearly so satisfactory for sealing windows.

Mineral oils don't dry, so wouldn't be a good basis for paint!

ok perhaps I didnt mean to say mineral oil. What I mean is modern oil
based paint, which I have always assumed are based on oil from an oil
well

Modern oil based paints form a plastic film on the surface but linseed
oil soaks in to some extent. Manufacturers recommendation is to
freshen up linseed oil paint after 5 years by wiping down with plain
linseed oil, so I assume the paint continues to be slightly permeable
to oil so the putty gets reoiled and doesnt dry out


I'm testing
this theory on my house and will let you know in 10 years time how the
putty + linseed oil paint combination performs

Anna
PS Its doing fine after 9 months ...

A lot depends on the thickness of the putty. On a casement window you
often have quite a deep rebate, but on sliding sashes it's usually
shallow (about 5mm round here). That amount is unlikely to stay soft,
especially on a south facing window. IME it's the main cause of rot in
this type of window, and has done the double glazing industry a huge
favour.