We had the exterior plywood soffits and fascias painted a couple of
years back.

There's a section where it's all peeled of, in giant flakes, right back
to the plywood, which is in fair condition. It's like the paint just
didn't 'stick' to the wood.

I'm going to take this back to bare wood and re-paint myself.

What should I do do ensure better adhesion?
Presumably I need to use the correct undercoat or somesuch.
Why did the previous paint job fail?

--
Ron

Ron Lowe wrote:
We had the exterior plywood soffits and fascias painted a couple of
years back.

There's a section where it's all peeled of, in giant flakes, right
back to the plywood, which is in fair condition. It's like the
paint just didn't 'stick' to the wood.

I'm going to take this back to bare wood and re-paint myself.

What should I do do ensure better adhesion?
Presumably I need to use the correct undercoat or somesuch.
Why did the previous paint job fail?

It could have been any number of things - a chemical treatment on the wood,
the plywood was damp prior to painting etc.

Give it a sanding down and make sure it's dry before painting, then just use
normal undercoat and gloss, 2 coats of each for a long lasting finish

On 24/03/2012 18:12, Phil L wrote:
Ron Lowe wrote:

I'm going to take this back to bare wood [...]

Give it a sanding down and make sure it's dry before painting, then just use
normal undercoat and gloss, 2 coats of each for a long lasting finish

Don't forget the primer - most important when starting from a bare surface.

--
Andy

Ron Lowe wrote:
We had the exterior plywood soffits and fascias painted a couple of
years back.

There's a section where it's all peeled of, in giant flakes, right
back to the plywood, which is in fair condition. It's like the
paint just didn't 'stick' to the wood.

I'm going to take this back to bare wood and re-paint myself.

What should I do do ensure better adhesion?
Presumably I need to use the correct undercoat or somesuch.
Why did the previous paint job fail?

My method would be:

Prepare the whole job by scraping and rubbing down to remove all loose
material and too feather-edge around missing paint, wash with white spirits
(removes grease etc) and allow to dry thoroughly.

Give all bare and problematical areas a coat of *aluminium* wood primer (see
link http://www.decoratingdirect.co.uk/viewprod/t/TORALWP/ ) and again allow
to dry.

Rub down primed areas and then give the whole job either:

A couple of coats of undercoat and one coat of gloss. OR one coat of
undercoat and two gloss coats. OR even two coats of each - obviously
rubbing down between coats.

On external works, I look for at least five years between painting jobs
(particularly along roof and hard to reach areas) and I tend to use two
coats each of undercoat and gloss to build up the paint thickness to give me
the 'life' that I want - along with ensuring proper preparation (and it's
the preparation that takes the time *AND* makes the finish along with good
quality materials [which are not necessarily the dearest or most well
known).

Hope this helps

Cash

On 24/03/2012 18:09, Ron Lowe wrote:
We had the exterior plywood soffits and fascias painted a couple of
years back.

There's a section where it's all peeled of, in giant flakes, right back
to the plywood, which is in fair condition. It's like the paint just
didn't 'stick' to the wood.

Was it originally bare wood, or wood coated with a melamine finish? I
had the latter on my garage and had the same issue, paint just wouldn't
adhere to it.

I covered it up with uPVC fascia boards instead though I now find,
looking at google, that special melamine primer is available.

--
Adrian C

On 24/03/2012 18:36, Andy Wade wrote:
On 24/03/2012 18:12, Phil L wrote:
Ron Lowe wrote:

I'm going to take this back to bare wood [...]

Give it a sanding down and make sure it's dry before painting, then
just use
normal undercoat and gloss, 2 coats of each for a long lasting finish

Don't forget the primer - most important when starting from a bare surface.

Actually I have seen this with new wood surfaces painted after treatment
with spirit based Dulux wood preservative after about 2-3 years. And it
doesn't seem to matter what primer, undercoat and topcoat system goes on
top of it.

I have a feeling that they had something in the mix that acts like a
mould release for the main paint film and it is related to the move
towards low solvent paint formulations. The behaviour is different to
trapped moisture under the paint which is also present but nothing like
as bad as these big flakes literally jumping off the woodwork.

It is mostly parts that face south and get the weather that flake off so
I guess it is some variant of thermal stress and flexure.

--
Regards,
Martin Brown

On 24/03/2012 18:09, Ron Lowe wrote:
We had the exterior plywood soffits and fascias painted a couple of
years back.

There's a section where it's all peeled of, in giant flakes, right back
to the plywood, which is in fair condition. It's like the paint just
didn't 'stick' to the wood.

I'm going to take this back to bare wood and re-paint myself.

What should I do do ensure better adhesion?
Presumably I need to use the correct undercoat or somesuch.
Why did the previous paint job fail?


Crap paint probably. Acrylics are ok for an undercoat but hopeless as a
topcoat

On 25/03/2012 09:46, Martin Brown wrote:

Actually I have seen this with new wood surfaces painted after treatment
with spirit based Dulux wood preservative after about 2-3 years. And it
doesn't seem to matter what primer, undercoat and topcoat system goes on
top of it.

What did the instructions for the preservative say about overpainting, I
wonder? Some preservatives are in quite oily carriers and take a long
time to dry out, so don't help with paint adhesion. FWIW Dulux do a
combined preservative-primer as part of their Weathershield system, and
it seems to be Good Stuff (IME):

http://dulux.trade-decorating.co.uk/...sheets/203.pdf

--
Andy