I have been repairing some windows but have noticed that the underside
of one of the stone window sills is very flaky and damaged.

Therefore I wish to stabilise this, rebuild it and finally paint it.

Any ideas on exactly how I should go about this? I thought about
brushing away as much of the loose material first then painting with
something to hopefully stabilse and stop most of the flakyness.

Would this be suitable? (Stabilising Solution Concentrate)

http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100147&ts=08315&id=13030

or would PVA do the job? Bearing in mind, this is an external job.

Once the surface is reasonably sound, I then thought I'd use either
concrete mix or external filler to rebuild the shape.

Finally sand off and paint.

Any comments on this?

If sandstone then definitely don't use any cement product as it reacts
and causes stone deterioration; this may be the cause of your prob in
the first place e.g. cement based pointing.
Best left alone - any attempt to improve it will be short term and
probably accelerate the deterioration. If its really bad then consider
a new piece of stone.

cheers

Jacob

nielsonj1976@yahoo.co.uk wrote:

> I have been repairing some windows but have noticed that the underside
> of one of the stone window sills is very flaky and damaged.

> Once the surface is reasonably sound, I then thought I'd use either
> concrete mix or external filler to rebuild the shape.


Use car body filler; works very well

David

Lobster wrote:

> nielsonj1976@yahoo.co.uk wrote:
> 
>> I have been repairing some windows but have noticed that the underside
>> of one of the stone window sills is very flaky and damaged.
> 
> 
>> Once the surface is reasonably sound, I then thought I'd use either
>> concrete mix or external filler to rebuild the shape.
> 
> 
> Use car body filler; works very well
> 
> David


Certainly does, but you need to use a former of some kind. Clamp some 2" 
x 1" where you want the new edge to be. Smear it with vaseline as a 
release agent, and possibly put a few screws in the old sill to act as 
posts.