Alternative to Hammerite ??

[Bill]

Hi all, I have 40m square of steel sheeting to paint, mostly still covered with its original paint but also with a fair amount of rust caused by scrapes and scratches, Obviously the ideal answer would be to sand it down, prime and paint but to be honest the finish does not need to be perfect so I am looking for a quick fix. Is there anything that could be painted on either as a primer or final coat that is not going to mind going on top of rust? All thoughts gratefully received, thank you.

[Adrian]

Bill gurgled happily, sounding much like they were saying:

Whatever you use, you need to clean it up. The only question is how thoroughly - and that depends on how badly you want to keep it.

I've just asked an online supplier a similar question regarding car undercarriage. Their answer was to clean it back "manually" (ie wirebrush etc sufficiently to clean all the flakiness and loose muck off, but don't worry about getting it all spanglingly shiny) and use Rustoleum 769. A chunk of change from £20/litre, mixed to whatever colour.

[Bruce]

That's a very large area, so whatever treatment you choose should not be an expensive one.

I would be tempted to remove any loose rust with a wire brush then use Kurust to stablise what rust is left behind. Then apply your chosen paint system, preferably finishing in a colour that won't show any areas of rust that break through. In other words, not white. ;-)

[Bill]

In message , Bruce writes

Indeed, a major consideration. :-)

I'm looking at Matt NATO green, should fit the situation perfectly, and it's relatively cheap :-)

for the comments.

>

[Bruce]

You're welcome.

[js.b1]

Wire brush tend to require brute-force angle-grinder rather than drill

- and remove a fair bit of metal too.

3M Clean N Strip XT (purple) discs are very good. 2-3 will strip an entire car of paint, corrosion, pitting to bare steel without removing much steel which might be important. Frost's Auto Restoration and probably fleabay do them.

Hammerite is good until water gets under it. Protection is how much are you willing to pay. True cold galvanising paint like Galvafroid works surprisingly well - you need to get to Sa2.5 (good 3M clean n strip, no dark mill-scale, not likely if corroded steel). It does require a primer on top & suitable paint since it is mechanically very weak - it is pure virtually nanoscopic zinc (and ridiculously heavy and priced accordingly). Zinc loaded epoxy works well, 2pk is available; commonly used in marine applications with micaceous oxide and so on. POR15 is good if you never intend to weld.

If this is a long boat, hire a media blaster - or perhaps see if you can get an attachment for a pressure washer, in theory they should exist but I have never bothered. That keeps the material wet which reduces the mess.

The 3M clean-n-strip in Purple XT form are like a sand blaster in their speed - very effective removal of everything except the steel. Best product for auto or similar "thin sheet metal" repairs ever. Galvafroid is pig ugly for auto use because it is thick and requires a suitable galvanised-metal primer because conventional car paint has no chance of sticking on top.otherwise.

Another alternative would be a metal-prep with suitable primer & paint on top. Comes down to the application. The zinc-epoxy can be roller applied and will at least give a good life. I assume the 40sq-m it can't be dipped?

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Bill saying something like:

Use dilute phosphoric acid, which is all Kurust is, to treat the rusty areas with, first.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "js.b1" saying something like:

Images of Kirk Douglas in 'The Long Ships', and that bloody horn racket.

Itym narrow boat?

[Stuart Noble]

Not exactly off the shelf though

[Bill]

In message , Grimly Curmudgeon writes

As found in Coca Cola apparently!

But apart from that a quick Google has not thrown up any easy suppliers of it. What sort of figure were you thinking of by saying "dilute"? Also any suggest sources? There is 85% 125ml available on Ebay but this is way outside my comfort zone. Where as Kurust maybe out side my finances for the amount required!

As to the question is it a narrow boat? Unfortunately not, it is a metal shipping container, a rather rust one :-)

[geoff]

In message , Bill writes

There you go ...

[Dave Liquorice]

Today bought some HG "Cement grout film remover" 1l for =A38.43 this according to the Safety Data Sheet is 15 - 30% Phosphoric Acid. For it's intended use you dilute 10:1 with water.

[JimK]

acid based alloy car wheel cleaner?

JimK

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Stuart Noble saying something like:

Milk parlour descaler, available by the gallon, is 30% phosphoric acid, afair.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember geoff saying something like: