Rust inhibitor .. which one to choose

The Lobster

The Lobster

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I'm putting up a trampoline for the kids. It's made of assume sort of galvanised steel. I want to coat the bolts with a rusty inhibitor so it lasts at least one Scottish winter. But it occurs to me that I could use it on external parts of the motorhome that are vunerable.. like the stabilising legs etc.

What's the best one to choose for general purpose use? At the moment I'm tending towards Boeshield T-9.

Thanks
 
Can you still get HOLTS (I think) RUST EATER.... Must be 40 years since I last saw it.
Supposed to turn rust back to metal!
Looked more like black rust to me.
Certainly prevented rust.
 
If you are after protecting metal to prevent it rusting, there are two options that really work.
1) High concentration zinc primer paint. This is like galvanizing the metal in that the zinc acts as a sacrificial anode coating.
2) Fluid film. This is made from Lanolin and is a creeping oil/wax like substance that prevents moisture and air getting to the metal thus preventing rust.

You either have to give something to oxidise instead of the steel, or you have to prevent the steel oxidising in the first place. I would avoid any other types of coating such as undercoats or paints or coatings as they can trap the moisture in and accelerate the process. It is worth spraying inside the metal tubes to prevent rust from attacking from the inside out. You will need to keep on top of it.

However, If you are want to fix rust that has already happened. The simple fact is you can't. Once something has started to rust it will continue no matter what you do. You can slow it down but you can't stop it. If you want to do a proper job you have to cut out the rust completely and replace with good metal.

That said you can do effective repairs that will last a very long time. Grind back or cut out as much as you can. Use some phosphoric acid based converter that will convert any remaining surface rust to a stable material. sand back then apply a zinc primer. You can then apply a normal paint coat or a fluid film coat at this stage.

Stainless steel is good, but even it will rust eventually if not of a decent quality and looked after :(

I have tried a number of rust cures/preventatives over the years and found them all to be of similar poor results. From Kurust to Dinitrol. The dinitrol was much much better than the cheap stuff but still ulimitamately failed.

The only thing that has worked on tests is the zinc primer. The best retarder of rust I found was fluid film. Look for a good quality primer with very high percentage zinc.

This is the fluid film I ordered. The test piece I sprayed 2 winters (Oct 2018) ago without any preparation hasn't rusted at all, whereas parts right next to it have.

Fluid Film AS-R 400 ml Spray Can, 3 pack with probe : Amazon.co.uk: Automotive

Fluid Film AS-R 400 ml Spray Can, 3 pack with probe : Amazon.co.uk: Automotive
amzn.to
 
This site contains affiliate links for which MHF may be compensated.
SIFTA SAM said:
The 'quality' of stainless steel can be checked using a magnet, where a high standard of stainless steel will show no magnetic attraction.
Click to expand...

Martensitic stainless steels will rust, Austenitic stainless will resist for much longer, Grade 316 is the one to go for.

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robnchris said:
Martensitic stainless steels will rust, Austenitic stainless will resist for much longer, Grade 316 is the one to go for.
Click to expand...
You might not be aware of AvE. This is the video I was referring to (or one of them).

 
Gromett said:
If you are after protecting metal to prevent it rusting, there are two options that really work.
1) High concentration zinc primer paint. This is like galvanizing the metal in that the zinc acts as a sacrificial anode coating.
2) Fluid film. This is made from Lanolin and is a creeping oil/wax like substance that prevents moisture and air getting to the metal thus preventing rust.

You either have to give something to oxidise instead of the steel, or you have to prevent the steel oxidising in the first place. I would avoid any other types of coating such as undercoats or paints or coatings as they can trap the moisture in and accelerate the process. It is worth spraying inside the metal tubes to prevent rust from attacking from the inside out. You will need to keep on top of it.

However, If you are want to fix rust that has already happened. The simple fact is you can't. Once something has started to rust it will continue no matter what you do. You can slow it down but you can't stop it. If you want to do a proper job you have to cut out the rust completely and replace with good metal.

That said you can do effective repairs that will last a very long time. Grind back or cut out as much as you can. Use some phosphoric acid based converter that will convert any remaining surface rust to a stable material. sand back then apply a zinc primer. You can then apply a normal paint coat or a fluid film coat at this stage.

Stainless steel is good, but even it will rust eventually if not of a decent quality and looked after :(

I have tried a number of rust cures/preventatives over the years and found them all to be of similar poor results. From Kurust to Dinitrol. The dinitrol was much much better than the cheap stuff but still ulimitamately failed.

The only thing that has worked on tests is the zinc primer. The best retarder of rust I found was fluid film. Look for a good quality primer with very high percentage zinc.

This is the fluid film I ordered. The test piece I sprayed 2 winters (Oct 2018) ago without any preparation hasn't rusted at all, whereas parts right next to it have.

Fluid Film AS-R 400 ml Spray Can, 3 pack with probe : Amazon.co.uk: Automotive

Fluid Film AS-R 400 ml Spray Can, 3 pack with probe : Amazon.co.uk: Automotive
amzn.to
Click to expand...
You’ve got far too much time on your hands, like most of us I suspect, but a useful informative post Non the less.(y)
 
This site contains affiliate links for which MHF may be compensated.
Are we still bolting this trampoline together??

Never mind I’m sure there will be grand kids coming along soon enough.
 
Gromett said:
You sounded like AvE then :D
Click to expand...

Never seen those utube vids, my knowledge of metals is purely from my engineering background.
A lot of people are misled in thinking Stainless Steel is all singing and dancing the answer to everything.
It's not, it's main property is it resists corrosion apart from that it has very little to offer, it suffers from cold shortness and also suffers from hot shortness making it difficult to work, ie. tap a thread into etc.

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robnchris said:
Never seen those utube vids, my knowledge of metals is purely from my engineering background.
A lot of people are misled in thinking Stainless Steel is all singing and dancing the answer to everything.
It's not, it's main property is it resists corrosion apart from that it has very little to offer, it suffers from cold shortness and also suffers from hot shortness making it difficult to work, ie. tap a thread into etc.
Click to expand...
It has some other excellent properties as well. Check out the SpaceX use of it in their new Starship. The starship was originally going to be advanced composites and aluminium. But SS works out lighter once you consider it's other properties.

I do however think SS is overrated for corrosion resistance. I much prefer galvanised in my personal experience.
 
Gromett said:
It has some other excellent properties as well. Check out the SpaceX use of it in their new Starship. The starship was originally going to be advanced composites and aluminium. But SS works out lighter once you consider it's other properties.

I do however think SS is overrated for corrosion resistance. I much prefer galvanised in my personal experience.
Click to expand...

Ahhh But Galvanised Pipework on an acid plant would never work, also as a sailor Stainless Steel fittings are far more superior to Galvanised.
Once at the London Boat Show I paid a lot of money for 100 mtrs of Stainless Chain, Chris my wife looked at me and said HOW MUCH...I replied wait till you see what we are going to do with it, whilst making a chucking over the side movement....:unsure:
 
robnchris said:
Ahhh But Galvanised Pipework on an acid plant would never work, also as a sailor Stainless Steel fittings are far more superior to Galvanised.
Once at the London Boat Show I paid a lot of money for 100 mtrs of Stainless Chain, Chris my wife looked at me and said HOW MUCH...I replied wait till you see what we are going to do with it, whilst making a chucking over the side movement....:unsure:
Click to expand...

When I talked about galvanised I was talking about it from a domestic point of view. ie for cars, trampolines, fittings etc. Acid plants and Boats are a different matter entirely and outside my wheelhouse if you will excuse the pun.

I have had SS bolts corrode on me so not overly impressed with them in general.
 
+1 for ACF50

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