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Best way to handle this rust patch...


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Hi All

 

I've got this patch developing on the side of the boat. I've previously just dabbed rust treatment on it but i need to do more....  I was thinking taping a square around it and lightly sanding, then treating it and painting but just wanted to check this is the most effective way?    I have the red paint and obviously the match will be way off since its red and faded!  its never going to look pretty or perfect, but just looking for best method!

 

thank you!

rob

 

 

20220211_162254.jpg

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Grind right back to bare metal, a little grinding tool in a Dremmel works well. The rust will extend under the paint so grind just enough to get rid of all the rust.

Two coats of Bondaprimer then several coats of suitable red. I am aware of the "big square repair" school of thought but I think a minimal round repair is less visible.

The grinding/paint removal will likely leave an obvious "dent", if you don't like this then a tiny bit of body filler will help, applied after the Bondaprimer, before the paint. 

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I use vinegar for rust but usually for things that can be dunked into receptacles full of it. For that, you could soak a lump of cotton wool, shove it on & cover with cling film for a few hours.

I use that technique for motorbikes & bicycles, old fuel tanks just get half filled & turned over.

Vinegar is dirt cheap from my local Chinese supermarket but you need to be able to wash it off & paint it quick 'cos it'll just rerust otherwise.

 

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On 13/02/2022 at 10:15, dmr said:

Grind right back to bare metal, a little grinding tool in a Dremmel works well. The rust will extend under the paint so grind just enough to get rid of all the rust.

Two coats of Bondaprimer then several coats of suitable red. 

 

Aren't you forgetting about undercoat? I once ignored the "primer, undercoat, topcoat" mantra and made the mistake of painting topcoats directly onto Bondaprimer. I painted the entire back deck, bulkhead and steel bench of my widebeam. None of the topcoat stuck properly. A good undercoat is like a tie layer between the primer and topcoats. I've also been told by Rustins that alkyd resin based paints like Bondaprimer should be left for a few weeks before keying and overcoating. 

 

I've stopped using the stuff now anyway. Every can I bought became congealed. One was even like that as soon as I opened it - like a weird jelly that you can't do anything with even with cellulose thinners.

Edited by blackrose
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5 hours ago, Cheshire cat said:

Get a diamond encrusted burr (grinding accessory) for a dremel. You can use it with a battery drill if you haven't got a dremel but it's less wieldy.

 

Use it to gouge out the rust then repair as above.

 

Blimey it's all getting a bit equipment intensive. What's wrong with a bit of sandpaper and a wire brush? 

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If you are keen,rust can be completely chipped using a sharp point chisel and a small hammer.................. poor paint jobs............I worked for a big sandblasters,and job after job the spec was for a single coat of hi build ....no undercoat............and unfortunately a lot of engineers dont seem to know which way is up......they design structures with dirt and rain traps ,often with such poor access ,that the steel is neither blasted or painted.

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I also comment much modern coating (paint) has such high dry film strength,that unless the surface is "keyed",they will come off in big sheets under the stress of sun and cold........this "keying" (called profile) is produced by air or roto blasting with steel grit in  a large blastroom.......not "water blasting with a random amount of sand in the stream".......note that grinding with a flap disc produces next to  no key at all,and furthermore,the abrasive grinds flat any key from previous blasting.

Edited by john.k
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8 hours ago, Cheshire cat said:

Get a diamond encrusted burr (grinding accessory) for a dremel. You can use it with a battery drill if you haven't got a dremel but it's less wieldy.

 

Use it to gouge out the rust then repair as above.

something like this?

 

Double Cut Carbide Carving Bits for Dremel, 10 Pcs Rotary Burr Set with 1/8” Shank and 1/4" Head Length for DIY, Woodworking, Engraving, Metal Carving, Drilling, Polishing : Amazon.co.uk: DIY & Tools

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5 hours ago, blackrose said:

 

Aren't you forgetting about undercoat? I once ignored the "primer, undercoat, topcoat" mantra and made the mistake of painting topcoats directly onto Bondaprimer. I painted the entire back deck, bulkhead and steel bench of my widebeam. None of the topcoat stuck properly. A good undercoat is like a tie layer between the primer and topcoats. I've also been told by Rustins that alkyd resin based paints like Bondaprimer should be left for a few weeks before keying and overcoating. 

 

I've stopped using the stuff now anyway. Every can I bought became congealed. One was even like that as soon as I opened it - like a weird jelly that you can't do anything with even with cellulose thinners.

 

Yes, I should have mentioned undercoat, I like Craftmaster high build and even with a fit of filler it helps fill the dent created by the grinding.

 

Bonda has changed and is not as good as it used to be, but still quite good. I agree about the jelly but I find some cellulose and a good stir sorts it out.

I assumed Rustins have recently acquired BondaPrimer?

I don't agree with the few weeks drying, a big Bonda advantage is that you can do two coats plus a first undercoat in an hour or so. Maybe they are confusing Alkyd and cellulose paints???

What does matter is that you cant put Bonda on top of Alkyd unless the Alkyd has had several days to go hard.

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6 hours ago, robtheplod said:

Probably ! Mine is a genuine dremel round ball head with industrial diamond chips on it. I can't see any online so maybe there are supply problems. Basically you need to be able to gouge the steel to clear out the rust as much as possible. Using a wire brush won't hack it. A small one in a drill or dremel will have filaments that are too bendy and the larger ones will make a mess of the paintwork as they remove far too much material, all in my opinion 😊

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I was looking at Dremel heads then found a Dremel 'copy' on Amazon - battery driven with lots of attachments for £19 so thats on order. I'm sure its not great quality for that price but i only have a few patches and it will prove if it will suffice or a better one is needed.... now i just need it to warm up a little!!

 

as ever thanks for everyone who always takes the time to advise me!

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I think you need some overplating mate. 

will need to strip the interior too

big job…

and then there’s the colour matching,

best respray the whole cabin to get a good job.

All in all very costly,

better get a crowd funding page ASAP. 
good luck 🤞 

 


 

 

 

 

😃

 

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Just now, Goliath said:

I think you need some overplating mate. 

will need to strip the interior too

big job…

and then there’s the colour matching,

best respray the whole cabin to get a good job.

All in all very costly,

better get a crowd funding page ASAP. 
good luck 🤞 

 


 

 

 

 

😃

 

That's re-assuring, I thought this might be a big job!  :)

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On 15/02/2022 at 08:13, robtheplod said:

 

This sort of thing is really good, and if you get the bigger ones in a proper die grinder (a dremmel is a sort of mini die grinder) then you can remove a lot of metal quite quickly. I think a standard Dremmel grinding tool would be a much safer option for a bit of rust removal, don't really want to put a hole in the side of the boat 😀

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14 hours ago, enigmatic said:

Cut out a diamond shape, repaint with contrast colour, all part of the design of the boat!

 

how do you go about repainting a diamond shaped hole?

 

I think the boat should be condemned - rust is like woodworm - once it starts you'll never get rid of it.

 

suggestion - trade the boat in as part exchange for a big GRP Broads cruiser and avoid narrow canals.  No need to check for osmosis - the hull won't fall apart, it'll just need less and less ballast over the years as the water improves the density of the lay-up. 

 

alternatively give up boating and have a couple of Hurtigruten holidays each year.

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  • 1 year later...

I use this to control rust on our narrowboat. Once applied you can leave it until you decide to paint. Just leaves the rusted area black. I used to buy it from SP Paints in Stockport, Manchester. Sadly they closed during covid lockdown. This new supplier is quite a lot dearer.

 

1st time I used it i applied it to the handrails. Before it dried it rained. I ended up with black streaks down the side of the boat. Over time they faded. 

 

FERROZINC is a high performance water thinnable rust converter.

 

https://www.hmgpaint.com/products/rail/primer/41/ferrozinc

 

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5 hours ago, Steve Manc said:

I use this to control rust on our narrowboat. Once applied you can leave it until you decide to paint. Just leaves the rusted area black. I used to buy it from SP Paints in Stockport, Manchester. Sadly they closed during covid lockdown. This new supplier is quite a lot dearer.

 

1st time I used it i applied it to the handrails. Before it dried it rained. I ended up with black streaks down the side of the boat. Over time they faded. 

 

FERROZINC is a high performance water thinnable rust converter.

 

https://www.hmgpaint.com/products/rail/primer/41/ferrozinc

 

I clicked the link and it said forbidden, I can't even open the HMG main page vis google

 

Edited by ditchcrawler
I like adding bits
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  • 1 month later...

Hi

I purchased mine from Tool Paint which was cheaper. It seems more watery than my previous supplier. I have used it and it looks to have done the job. Rusted area has turned black. It has arrived in a plastic paint tin.

Tools-paint.com

Tel: 01753 684084 / 686888

 

At my home mooring the neighbouring boat uses Owatrol oil. She rubs it into the rust. 

 

Hope this is helpful 

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