Repainting metal garage doors
Craig Bruce
really dull and is flaking in places (showing the previous paint
job). I'm determined to sort them out this summer and as a
result need some advice on preparation and painting....the
lazy way.
I want to ensure I get a decent (lasting) finish on the doors, so,
as I already have flaking paint in some areas I want to strip the
doors as much as possible - question No. 1:
Will the sandblasting kit available for my Kew pressure washer
be up to the job - or will I go through so much sand it isn't
worth it.
Question No. 2 (plus 1b):
I could find many uses for air tools - how easy will it be to get
paint suitable for use with an air gun to paint the doors ?
Does the paint have to be water based ? and doesn't that
imply I can't use it for external use ????
If I shell out on a compressor (Screwfix have a decent enough
kit at around Ł130), is there the potential to use that for
sandblasting ?
I really can't face sanding the doors - mostly due to the fact
that they are 'grooved' and I don't think I'd get a good enough
finish.
TIA
Craig
cbr...@nortelnetworks.com
Norman Billingham
Craig Bruce wrote:
> The paint on my metal 'flip-up' garage doors is starting to look
> really dull and is flaking in places (showing the previous paint
> job). I'm determined to sort them out this summer and as a
> result need some advice on preparation and painting....the
> lazy way.
>
> I want to ensure I get a decent (lasting) finish on the doors, so,
> as I already have flaking paint in some areas I want to strip the
> doors as much as possible - question No. 1:
>
> Will the sandblasting kit available for my Kew pressure washer
> be up to the job - or will I go through so much sand it isn't
> worth it.
>
> Question No. 2 (plus 1b):
> I could find many uses for air tools - how easy will it be to get
> paint suitable for use with an air gun to paint the doors ?
> Does the paint have to be water based ? and doesn't that
> imply I can't use it for external use ????
I did this last year and half wish I'd just bought new doors!!
If the paint is flaking and you really want to get a smooth finish then
you have to get it all off. Sandblasting IMHO is far too dangerous to
your lungs to do on a job like this and the preesure washer wont fetch
it off. Burning is fast but distrorts the metal of the door. I did
mine with chemical stripper followed by a wire brush on a disc grinder.
A stadard single door took near enough 2 days work to strip.
I repainted with Hammerite smooth paint on top of their primer. I'm not
displeased with the result but choose a cool, dull day - the paint dries
in seconds if the metal is hot and you can't get a decent finish.
However you do it, its a nasty, horrible and slow job.
Peter Parry
<cbr...@nortelnetworks.com> wrote:
>Will the sandblasting kit available for my Kew pressure washer
>be up to the job - or will I go through so much sand it isn't
>worth it.
More importantly it will go through the galvanising so comes under
the heading of "really dim idea" !! Use a chemical paint stripper if
you must and a paint specifically meant for galvanised surfaces.
Paint adheres better if the galvanising is exposed to the weather for
a week or so so don't rush things.
>Question No. 2 (plus 1b):
>I could find many uses for air tools - how easy will it be to get
>paint suitable for use with an air gun to paint the doors ?
Easy, but for most thick paints you need a gun with a pressure feed
to the paint supply which pushes the paint through. Costco used to
have quite a nice kit of about 4 spray guns for about GBP40 including
one pressure fed. Ideal for my spraying ability.
>Does the paint have to be water based ?
No.
>and doesn't that
>imply I can't use it for external use ????
No.
>
>If I shell out on a compressor (Screwfix have a decent enough
>kit at around £130), is there the potential to use that for
>sandblasting ?
Not really other than spot blasting (1cm areas). Look at the air
capacity required for the tool (say 5cfm) and double it. Now look at
the compressor rated maximum delivery and halve it. You are now
close to reality, so a 5cfm device requires a compressor rated (in
the adverts) as 20cfm for sustained use (or at least that's my
experience!!).
>I really can't face sanding the doors - mostly due to the fact
>that they are 'grooved' and I don't think I'd get a good enough
>finish.
DON'T sand them - they are probably galvanised
--
Peter Parry.
http://www.wpp.ltd.uk/
gerant
first primer coat of paint is applied. The rust-proofing is either a
'phosphate' treatment or galvanising. The point of this comment is that if
you strip your door completely either by sanding or sand-blasting you risk
damaging the rust-proofing coat.
Your 'Kew' pressure washer uses water-entrained sand to do the sand blasting
and if you manage to remove all the the paint you will almost certainly
damage the original rust-proofing and you will then have to deal with the
rust which will result from the sand / water mix used to do the sand
blasting.
As far as the performance of your 'Kew' washer is concerned, I found that
mine was very effective for small intricate cleaning jobs but I believe that
a big job like an 8' x 7' door would leave you knee-deep in wet sand and big
bill for clearing your drains!
Assuming that you manage to strip the door, the choice of paint for
re-painting is no problem. You can spray almost any paint provided that it
is suitably 'thinned'. The usual recommendation is that you should 'thin'
the paint until it has a milky consistency. This applies particularly if you
are using normal household gloss paints. Be warned though that it's easy to
make a complete mess with spraying if you don't practise first. Suitable
paints are normal household gloss, and 'coach paints' such as 'Berger' or
'Tekaloid' both of which can be bought from good motor vehicle paint
suppliers. Water based paints are certainly not necessary and I doubt if you
would find one suitable for this purpose.
A compressor suitable for sand-blasting usually requires a minimum delivery
of at least 8 CFM (cubic feet per minute), but you need to check the details
of specific makes to be sure. I don't know the performance of the 'Screwfix'
compressor but they will give you the details if they're not already in the
catalogue.
My advice would be to use a chemical stripper such as 'Nitromors' or
alternatively rub down to a good original coat and work from there.
I hope this gives you some idea of what is possible - I'm sure others may
add to or improve upon my suggestions.
gerant
Max Bone
Can't really add much to the other replies...
You indicate that the coating is losing adhesion (flaking) between this
decoration and a previous decoration, rather than back to the galvanised
metal. Once you get intercoat adhesion problems the only sure way to
solve them is to strip back and start again, however it seems like
overkill for what you describe as 'flaking in a few places'. In this
case I'd just scrape back all loose areas as best as possible, wash
down, rinse, dry. Then prime all areas with a good adhesion promoter
such as Zinsser Bulls Eye 123 (which is water-borne)
http://www.decoratingdirect.co.uk/viewprod/z/ZINBE
and overcoat with your chosen finish, water-bornes or solvent-bornes as
you see fit. I've never sprayed with anything other than professional
airless or HVLP equipment, so can't advise on the equipment you are
considering... but most coatings should spray ok once thinned - usually
10-20% but consult the manufacturers data sheet for recommended %'s.
As for using water-bornes outside, some of the best external low-
maintenance coatings are based on water-borne acrylic resins and they
would be a good choice for you here, although you should bear in mind
that they are not as resistant to mechanical wear and tear, but offer a
great many benefits over alkyds.
Regards
--
Max Bone Decorating Direct Ltd
http://www.decoratingdirect.co.uk/
hundreds of products - secure online ordering - delivered to your door
hugh mitchell
Craig Bruce wrote:
> The paint on my metal 'flip-up' garage doors is starting to look
> really dull and is flaking in places (showing the previous paint
> job). I'm determined to sort them out this summer and as a
> result need some advice on preparation and painting....the
> lazy way.
Craig,
I spent a few hours stripping my garage door on Sunday.
Used a hot air gun and it worked far better than the test piece I did
with Nitromors.
To deal with the ribs, I made a small scraper, that fitted the profile.
A piece of alluminium screwed to a simple wooded handle worked well. It
does not need to be particularly sharp as the hot air gun effectively
lifts the old paint off the surface, leaving the manufacturers original
finish.
Where I scraped down to the galvanised finish, I primed with a non
ferrous metal primer.
Undercoats and top coat next weekend.....
Hugh
Craig Bruce
news:vtipxGAv...@decoratingdirect.demon.co.uk...
>
> Can't really add much to the other replies...
And no wonder ! I find myself yet again surprised and impressed
by the level of knowledge and helpfulness in this group.
Taking all advice on board I'll look at whether the area around the
flaking paint can be suitably prepared to a smooth finish, before
potentially resorting to Nitromors-ing the whole lot.
As for painting, I'll give spraying a try (probably practice on the
inner garage walls which could do with a lick anyway, and I'll
invest in either the 2HP 25ltr Screwfix compressor:
http://www.screwfix.com/product.phtml?5586
or save a couple of pennies and get the 1.5HP one with tools
thrown in:
http://www.screwfix.com/product.phtml?8584
Cheers,
Craig
cbr...@nortelnetworks.com
Peter Parry
<cbr...@nortelnetworks.com> wrote:
>As for painting, I'll give spraying a try (probably practice on the
>inner garage walls which could do with a lick anyway,
Don't forget if it is galvanised you need to use a paint (or at least
a primer) designed for galvanised surfaces otherwise the new paint
will quickly flake.