Rust inhibitors

[Sailfree]

Firstly thanks for all the good advice I have received. I am sure all the advice posted has also helped many others.

Thru Hull fittings received from ASAP, grinder, multitool & cone cutter (up to 48mm) all ready to go! Plud Gas & wide jaw sort adjustable as backup. Loctite 572 and PU40 bought and will be used.

Next problem

Last year keel was showing rust. Best I could do was grind it off and used Hammerite then antifould. Will see how it has fared this year. I know I should aim to get the rust areas cleaned to SA2.5 but I found rust areas a bit porous. After this year if necessary I will have a go wth a needle gun but this year due to time constaints I intend to grind any off as best as possible and try a rust inhibitor. Made a note from prevous threads of "Fertan" being recommended. Many years ago I used another product that was meant to neutralise te rust, then wash with water (sightly acidic?) then paint.

I am not looking for Zinc rich primers but rust inhibitors. Can anyoone suggest ones that they have had some success with please?

 

[Tintin]

Fertan every time

 

[alahol2]

+1
Fertan does seem to work as well as any to neutralise the rust.

 

[Sammy Lou]

+2. Fertan used on my southerly keel and grounding plate by Symblast after shot blasting this winter - very impressive. The keel was extremly rusty before blasting and the metal has sat bare for the past three months with only fertan applied and there is no signs of rust at all

 

[theoldsalt]

I have used Hammerite Kurust for years with good results. It is very convenient as it can be over-painted after 3 hours and requires no rinsing off.

I am willing to try another product.

Is Fertan any better (and how) for the extra cost?

 

[alahol2]

I have used Hammerite Kurust for years with good results. It is very convenient as it can be over-painted after 3 hours and requires no rinsing off.

I am willing to try another product.

Is Fertan any better (and how) for the extra cost?

I think they are both Tannic acid based. According to the SDS sheets Kurust has 2.5 - 10% tannic acid, Fertan has 10 - 30%. Whether that justifies the extra cost or not I have no idea.

 

[SteveTibbetts]

How much fertan would I need to buy for the keel on my westerly 31? May be 4 sq meters ? But I'm rubbish at estimating from a memory of a keel I've only seen once.

 

[pcatterall]

A question rather than an answer I'm afraid! I have used kurust and similar over the years, where the steel had pockets of rust my theory was that if I cleaned down to bare clean metal and got the loose rust out of the pits and then applied kurust to all and then cleaned off the residue kurust from the smooth non rusy metal then overpainted all I would get the best results. Is there different advice nowadays?
I will remember the good comments here about Fertan.

 

[alahol2]

Having a read round...
Wikipedia... "Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion. Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place. After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion. Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue. It should also be used with care on objects with copper alloy components as the tannic acid can have a slight etching effect on these metals.

Tannic acid is also found in commercially available iron/steel corrosion treatments, such as Hammerite Kurust."

Perhaps this is the best way to buy it... http://www.ebay.co.uk/itm/100g-Tannic-acid-pure-grade-pure-product-superb-quality-/141135542377?pt=UK_BOI_Medical_Lab_Equipment_Lab_Supplies_ET&hash=item20dc557869

 

[nigelmercier]

cone cutter (up to 48mm) ...

Where did you get that?

Fertan: http://amzn.to/1hW5w2x
Tannic Acid: http://amzn.to/MxzSJZ

 

[Sailfree]

Where did you get that?

A few years ago in Cromwell tools. Bought 2 the 48mm step cutter is the biggest one. Been looking for a 60mm but only seen them on US websites.

 

[nigelmercier]

A Been looking for a 60mm [cone cutter] but only seen them on US websites.

I'm going to the US at the weekend, I'll have a look in Home Depot.

 

[ECLIPSE]

Phosphoric acid...... did a similar job on my Achilles. Bought the stuff from a hardware shop in Maryport......it was one of a range of bottled products labelled as a rust remover, and very capable it was too. Turns the surface rust black and hard.

 

[nigelmercier]

Phosphoric acid... rust remover ...

.

 

[AndrewB]

Another vote for Fertan, worked better for me than phosphoric or oxalic acid rust converters. My method was to apply it to the bared surface, after chipping away loose rust, then when the Fertan had dried, wash it down and then power wire-brush off the residue. If necessary repeat. Less wasteful of good metal than grinding out rust.

If you haven't tried it be warned it can be rather messy and will stain paintwork and GRP if not quickly cleaned off. I have had mixed results applying epoxy paint directly over converted rust (same is true with other converters) which is why I like to wire-brush it clean.

 

[KellysEye]

>I am not looking for Zinc rich primers but rust inhibitors.

Having owned a steel boat rust inhibitors don't really work the rust comes back. As I've mentioned before go back to bare steel and use two coats of zinc rich epoxy primer.

 

[Tintin]

>I am not looking for Zinc rich primers but rust inhibitors.

Having owned a steel boat rust inhibitors don't really work the rust comes back. As I've mentioned before go back to bare steel and use two coats of zinc rich epoxy primer.

That is the best advice, but I have settled for an annual quick fix on my keel in the few spots. Scrape, Fertan, 2 x primocon, then antifoul

 

[KellysEye]

> As I've mentioned before go back to bare steel and use two coats of zinc rich epoxy primer.
>>That is the best advice, but I have settled for an annual quick fix on my keel in the few spots. Scrape, Fertan, 2 x primocon, then antifoul

Why not do it properly it saves work time and an annual problem?

 

[SlowlyButSurely]

I've had steel boats for the last 36 years, current boat for the last 28 years. Over the years I've tried all these gimmicks (including Fertan) in a futile search for something cheap, simple and effective but I have found them all to be a complete waste of time and money.

I have found Primocon to be pretty good, but you really need about 5 coats for it to last a few years. The Fertan won't make any difference in my experience.

The only thing that really works is epoxy. Obviously the better you prepare the surface the longer it will last but you don't need to get back to bare shiny steel if you use something like Jotun Jotamastic which will stick to rust as long as it isn't flaking. A quick grind with a wire brush in the angle grinder to remove the worst of the rust and 3 coats of Jotasmatic is all I ever do.

Have a word with the chap at SML.

 

[Zagato]

'Sliowlybutsurely' It sounds as though you are not getting the deep rust off and are just trying methods to cover the rust up before it comes through again.

These rust acid converting treatments don't miraculously soak into rusty metal, as has been said you need to get the main rust off and then use Fertan or which ever product you choose to kill/acid convert the remaining 'surface rust'.

I agree with 'KellysEye' get your keel blasted back or however you want to get the rust off, acid treat then galv/zinc coat. Epoxy and Primacom just cover over rust and trap rust. Better the zinc is being eaten away not your keel which is what it is designed for of course!

As an aside I have done a rust test with ACF-50 & an acid rust convertor from Dinitrol (I rust convert Defenders!) and both products are still doing the job after 2.5 years. You do have to prepare the metal properly though and get most of the rust off - these products don't work with thick rust. Another vote for Ku -Rust by the way and it can be used as a top coat with a few layers.

You need a rust convertor not inhibitor...

This is ACF-50 on a SAAB 96 bulkhead. It actively kills the rust for up to a year then leaves a coat over the top of your treated area stopping oxygen getting through like a layer of paint so you won't need to re-treat. It's ideal for areas where you can't physically get at the area you want to treat - inside scuttles for instance or small box sections! It's pricey so for large areas I would go for the normal rust convertors which can be got in £5 sprays cans with extension nozzles to 25 lires commercial containers.

The black blob is sealant not rust! Forget wire brushing get a screwdriver and dig off the rust :encouragement: