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ceramic zinc primers for metal boats
On 4 Jul 2003 08:26:23 -0700, (jalborey) wrote:
In your case go the thicker coat - it gives you more meat to sand off
and degrease when you are ready for it-
It will oxidise, so you want to sand off this layer, which will then
take it down quite a bit . The longer its outdoors, the more oxide.
You need to think more in mechanical performance than just plain
adhesion - some paints systems are centered around abrasion resistance
- Such as cars which get polished a lot - so they go for a hard
surface - But for impact you want a soft "rubber"surfact - self
healing - and for some others a sheading or self cleaning - system -
But for a primer - its as much about the acid etch - as this really
bites into the metal, better than just a surface scratching.
A simple test for your primer - just give it a tap with a ball
hammer, observe how it flattens and dents, and how much it can take -
- and or it breaks away from the surface - if the "decreasing" has
been done well - it should just squash up and give an impression - but
if it breaks away, its a warning something isn't right. you can also
score a piece, with a knife, to see if you have a nice V shape -or
again it lifts and crumbles on the edges - this can indicate too much.
filler in the paint, not applied properly, or not cleaned, prepared
properly. - or too much paint on.
Also the ceramic in the paint only goes a small way to solving the
welding problem - What happens is the hot metal fries the paint so you
have this zone near the weld- if you cannot hold your hand on it -
then the paint in that area is stuffed - so it pays to check how far
back you sand- before the paint lifts on you - ceramic in the paint
only gives you a little extra - You can use modeling clay -
put some in a bucket, for when you ready to weld slap a roll of this
on your paint - to suck up the heat - it will wash off and you can
reuse it- easier to use than chill bars - But check the edge of the
paint for scorch marks and crumbling - until you get back to the good
stuff. The wet clay can slow the paint burn down.
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