Tuesday, 20 August 2013

Using Fertan to treat rust for the first time

Today I decided to empty the under-well-deck storage area and treat it to a coat of Fertan, a rust converting chemical. I'd bought a litre of the product at the National Festival last month with this job in mind.

With the beer, wine and paint tins removed all that was left was the ballast.

The rust is all too obvious. It had been flaking off and covering everything with bits.

This is where the pipe from the water tank emerges: the strainer has handy isolation valves either side.

The ballast consisted of 61 engineering bricks. I don't know how much it weighs, but I knew I'd shifted them when I'd done it!

The next stage of preparation was to sand down the loose rust. This was a very noisy job as my head was inside the enclosed steel area I was sanding. Oh, and my hair turned orange. After sweeping up the rust I then had to dampen the rust prior to painting on the Fertan. This seems counter intuitive, but the stuff needs water in order to work its magic.

The head torch was as invaluable as ever.

At last, I could actually apply the Fertan! My first thought when brushing it on was Kurust. It had the same phosphoric acid smell as that evil grey stuff I used to paint on 1100s and Minis to get them through the MOT in the 1970s.

The smell was pretty strong in that small space: every so often I had to come out to breathe in some fresh air.

And this is what happens to the rust. In a few minutes it turns black, and looks as if it has been freshly painted that colour.

When I'd left it for a while I saw several areas I'd missed. As you're painting wet onto wet it's impossible to see where you've been - and I was probably too stingy with the Fertan anyway. It was an easy job to re-dampen the missed bits and re-apply the Fertan.

Now it's a case of letting it all dry. We have to move on from here tomorow as we're on a 48 hour mooring (at Cosgrove), so I brought all the ballast inside the boat. (Bad planning to do this on a 48 hour mooring!) If I'm going to paint what I've done I have to do it within three months. I don't know what will happen if I don't paint - it'll probably go rusty again, I suppose.

On to Stoke Bruerne tomorrow.


Paul (from Waterway Routes) said...

"Mr Fertan" had his stand next to ours at Crick and I'm sure he said you had up to six months.

Val Poore said...

It looks quite impressive! Strange that you have to wet the area first tough!

Halfie said...

Paul, oh no! That means I can delay painting even longer!

Halfie said...

Val, first impressions are good.

Trevor Potter said...

Paul is correct, Fertan rust converter leaves a zinc phosphate coating behind that prevents rust for 6 months. Ideally you would prime and/or paint before that time for a permanent solution. My company is the North American distributor for Fertan and we have clients using it on bridges, steel ships, classic cars. You can purchase it at: www.fcpeuro.com just search Fertan.

wargamepainter said...

Hmmm... I found Fertan to not work reliably.
I treated a 3.5 ton van chassis after shotblasting it.
Just to get into any stubborn areas and as a rust preventer.
Sometimes it seemed to work but other areas it went black but underneath their was a lot of rust that was not originally there.
Despite scrubbing the fertan areas and cleaning before epoxy then eurothane 2k top coat I got areas just flaking of.
i.e. the bond between the fertan and the epoxy was poor.
Maybe it was my poor prep but with the rust blooming and the odd area just flaking off in little sheet areas I would not trust fertan again.
Most all serious automotive body folk say sandblast, get rid of all rust then acid etch or epoxy onto clean bare steel.

I certainly regret not going that route as the signs are not looking good, my expensive epoxy and 2k topcoat won't do much when they pop off the fertan layer.

Also Fertan is very expensive and the post apply prep is vague/sketchy... rub off dust, but not too hard?? how hard is hard.

I hope some areas are better and hoping most will hold up but really I should totally strip and restart. Just don't have the heart as it's just trying to stop the march of the rust and cosmetic.

I think metal prep or straight epoxy in sections would have been better.

wargamepainter said...

Also my theory about the apply water etc is the water causes an acceleration in surface rusting. By treating with water first or with Fertan this causes flash rusting giving the Fertan something to convert into the black oxide layer.

I agree that there does seem to be a bright layer deposit under the black layer but basically the layer depends on causing flash rusting all over then converting this.

Also there is a statement from a paint corrosion expert on the web to the effect that this does not work on large areas effectively.
I think most rust converters do convert rust but don't offer a good solution. Non seem to provide a good substrate to paint onto.

Halfie said...

Wargamepainter, thanks for your comments. It's good to have another point of view. Where I used Fertan was inside a space used just for ballast and storage of things that don't mind getting cold or damp (beer, wine, paint brushes, paint tins etc). So it's not too important if it doesn't work. But it does seem to have worked, in that the area is still mostly black with little rust showing through, despite my not having painted it (as I said I would - oops!).

On the other hand I have also used Fertan to treat rust patches bubbling through the paintwork prior to repainting. I'm not very good at finishing jobs once started, so I Fertanned and primed but didn't get round to the gloss layer. These areas are going rusty again, unsurprisingly. I think that the only sure way to fight rust is to get back to bare metal and paint immediately, which is what you were attempting with shotblasting. In my days trying to keep old rusty cars on the road I would use products such as Kurust, as I have mentioned, before filling and painting. It was never successful - the rust would always return where I treated.

Still, as I have a lot of the stuff left, I will carry on using it. Just need some warm dry weather ...