Never painted ali before and I will have some cast ali guttering to repaint.

The plan is to pressure wash the guttering sections on the ground (they will
be off anyway) to remove crud and loose paint. Sound paint stays on.

The finish is to be black.

I'm not sure of what brand of etch primer and top coat to go for.

Also - does it matter if you etch-prime over exisitng paint, or do you just
avoid those parts?

Cheers!

Tim

--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"A fanatic is one who can't change his mind and won't change the subject."

On Oct 27, 6:39*pm, Tim Watts wrote:
Never painted ali before and I will have some cast ali guttering to repaint.

On 27/10/2012 19:39, Tim Watts wrote:
Never painted ali before and I will have some cast ali guttering to repaint.

The plan is to pressure wash the guttering sections on the ground (they will
be off anyway) to remove crud and loose paint. Sound paint stays on.

The finish is to be black.

I'm not sure of what brand of etch primer and top coat to go for.

Also - does it matter if you etch-prime over exisitng paint, or do you just
avoid those parts?

I used a zinc chromate primer bought from a marine chandler and intended
for boat use. That was on new aluminium guttering in the 1980s. It is
still sound, but I don't recall the make this far down the line, even if
it is still made.

Colin Bignell

Nightjar wrote:

I used a zinc chromate primer bought from a marine chandler and intended
for boat use. That was on new aluminium guttering in the 1980s. It is
still sound, but I don't recall the make this far down the line, even if
it is still made.

Probably International if it was for a boat.

http://www.mailspeedmarine.com/marin...ional%20Paints

Tim Watts wrote:
[snip]

Also - does it matter if you etch-prime over exisitng paint, or do you just
avoid those parts?

You can't etch prime over existing. Ideally you should take the paint back
to bare alloy. When sanding it is best to use aluminium oxide paper and
avoid the use of wire brushes. The brushes leave short bits of steel
embedded in the alloy and this will cause corrosion.




--
€¢DarWin|
_/ _/

Steve Firth wrote:

Tim Watts wrote:
[snip]

Also - does it matter if you etch-prime over exisitng paint, or do you
just avoid those parts?

You can't etch prime over existing. Ideally you should take the paint back
to bare alloy. When sanding it is best to use aluminium oxide paper and
avoid the use of wire brushes. The brushes leave short bits of steel
embedded in the alloy and this will cause corrosion.


Thanks Steve - that is something I would not have figured out - and I would
have tried a wire brush at somepoint.

I will see how far I get with a pressure washer to take off the grot and
flaky paint - I guess if there's a lot of paint left I will just have to
prime upto sound stuff - I don't have the spirit to be sanding everything -
there's 30m of the stuff.

Finish is not vastly important - just want it "generally black" and "mostly
not falling off" - which is why I'm reusing the ali

Unless of course I could get a wet sandblasting attachment for the pressure
washer.....

Cheers!

Tim

--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"It would be better to live under robber barons than under omnipotent
moral busybodies."

In message
Tim Watts wrote:

Never painted ali before and I will have some cast ali guttering to
repaint.

The plan is to pressure wash the guttering sections on the ground (they
will be off anyway) to remove crud and loose paint. Sound paint stays
on.

The finish is to be black.

I'm not sure of what brand of etch primer and top coat to go for.

Also - does it matter if you etch-prime over exisitng paint, or do you
just avoid those parts?

Cheers!

Tim

It is possible to apply acid etch over original paintwork but it may
also react with existing paint (and has no effect) particularly if it is
a synthetic base.
Acid etch primer in many instances can be applied over recent paint
finishes if it is very lightly sprayed over the top but not brushed on,
areosol and brushing etch primers are available on the market, the spray
type will dry very quickly which should help avoid solvent penetration
or reaction which is the main cause of paint reactions.

Acid etch primer should also be applied very sparingly (one coat only)
and the overlapping edges can simply be scuffed off with a piece of 600
paper, acid etch only needs to be inked over the surface to provide a
suitable key, it does NOT need a heavy coating to obliterate the
surface.

Any modern alkyd type synthetic gloss paint will suffice for guttering,
but you should still use a synthetic primer before the gloss.

Stephen.

--
http://coachpainting.info
From the Wirral Peninsula.
Coach painting tips and techniques + Land Rover colour codes
"Whatever is rightly done, however humble, is noble". Henry Royce

In article , Tim Watts wrote:

Unless of course I could get a wet sandblasting attachment for the pressure
washer.....

You can (at least for some brands of pressure washer)
e.g. http://www.tooled-up.com/Product.asp?PID=120850
Don't expect it to be as effective as a proper sandblaster though.