Total NAC: Rust paint

[Marc Boucher]

Painter started yesterday, on one balcony which I supervised. After grinding 
off any loose rust and paint, he put the rust converter in his spray gun and 
began spraying.

The amount of rust converter that was required to coat everywhere was 
surprisingly high. Since we're talking about railings, its not surprising 
that a lot more is required when spraying than when using a brush. But at 
this rate, we would use $4000 of rust converter.

He says that he prefers spraying because it gives an even coat everywhere. 
So he will simply turn down the rate at which it sprays the converter in 
order to cover everywhere with what we have.

Only about 10% of the railing is rusty, and that's been ground down. The 
rest is the original paint, which has been left on since there's no sign of 
rust. Spraying that 90% with rust converter does give everywhere a smooth 
coat. It does etch the old paint which the documentation says will serve to 
prime the old paint.

But I'm thinking that a better strategy would be to only put rust converter 
on areas where there's rust, and/or rust that's been ground to metal. We 
would get more rust converter on these spots, the spots that turn black, but 
at the expense of using it as an expensive 'etch/primer' for the old paint. 
The old paint could be painted over in a standard way (either just straight 
paint, or if needed a standard primer then enamel paint).

Which of the two options above would you recommend...thin layer of rust 
converter everywhere, or save it and focus it on the rusted areas?




--------------------------------------------------
From: "Marc Boucher" <mboucher70 at hotmail.com>
Sent: Friday, June 17, 2011 1:22 PM
To: <quattro at audifans.com>
Subject: Total NAC: Rust paint

> This group has always seemed to have technical knowledge on all fronts so 
> I'll take a shot at this.
>
> Need to repaint rusty metal railings outdoor.  Have a number of options 
> recommend to me.  Any thoughts among these?
>
>
> 1.) top of the line
> a.) remove all rust-sand to bare metal
> b.) apply Zinc for cathodic protection (can you recommend a few names of 
> products)
> c.) Anodic passaviation - 100% acrylic exterior membrane paint (can you 
> recommend a few names of products?
>
> 2.) The method recommended by the PPG rep (with the caveat that it had to 
> be done right)
> a.) Remove loose rust then apply 2 coats of rust converter
> b.) apply 2 coats of their epoxy paint (Amerlock)
> c.) apply 1 coat of their polyurethane paint (Amershield). (PPG also makes 
> Pithane which is Urethane based...I'll check why he didn't mention that)
>
> 3.) Benjamin Moore Alkyd Enamel KP22 (Industrial productwith Titanium 
> Dioxide, 394 g/L VOC) (an alternative is Rustoleum)
> a.) Remove loose rust then apply 2 coats of rust converter
> b.) paint with BM Industrial Enamel KP22. The painter recommends 1.5 coats 
> of enamel...1 coat, then touch ups.
>
> 4.) Benjamin Moore Exterior Alkyd Enamel 133 (although the name says 
> exterior, the spec sheet describes it as Interior/Exterior...so presumably 
> it’s not a high VOC content, but that’s not listed on the spec sheet.
> a.) Remove loose rust then apply 2 coats of rust converter
> b.) paint with BM Exterior Alkyd Enamel. The painter recommends 1.5 coats 
> of enamel...1 coat, then touch ups.
>
> 5.) Local brand of Exterior Oil Based Enamel. Our painter points out that 
> Benjamin Moore is always more expensive than local brands ($70/gallon for 
> BM vs. $50/gallon for a Canadian brand (Sico). He feels that the added 
> expense isn't justified given that we're already using multiple coats of 
> rust converter. Since he's being paid for labor separate than for paint, 
> his motivation for recommending the less expensive paint would not be to 
> maximize how much he takes home from the job.
> a.) Remove loose rust then apply 2 coats of rust converter
> b.) paint with the oil-based enamel. The painter recommends 1.5 coats of 
> enamel...1 coat, then touch ups.
>
> Thanks for any thoughts
>
> MC
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