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Micaceous Iron Oxide vs. Bitumen


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Hi lovely helpers,

The inside of my boat has been breeding insane procrastination. Hoping someone can help!

I've read through lots of the posts here, but just to be sure here is the unique situation of similar nature.

I have an old boat, it had sunk before I got it, and the interior was full of rust - totally stripped, no ballast so quite ideal.

First, I hit the chunks of flake with a crow bar, then a chipping hammer, then an angle grinder, then some sand paper. After I rid all the loose flakes I rinsed it with vinegar and potato, which was pretty effective.

There are various remnants of different paints throughout. Mostly a kind of red oxide, and then at the front possibly a bitumen, but I think under all of that is a grey/blue paint.. possibly a zinc thing? 

Can only attach one photo, will try to add more to clarify.

I was given some Micaceous Iron Oxide, and feel hesitant to waste it. Not sure if its similar to Red Oxide, or if it prevents rust coming through?

My ideal aim, is to use a paint to seal the rust and protect the metal, so that I can prevent the boat rusting from the inside out. While the boat is stripped it is the best opportunity to do the best job I can.. but I've been hesitating for way too long.

I've started grinding off what seems to be the bitumen. As I've seen in some posts the best prep is bare steel, and I really want to do the best I can. I have time but not so much money.

Any advice much appreciated. Any knowledge about Micaceous Iron Oxide also would help a lot (can't seem to find much info about its relation with rust or bitumen, whether its best on bare steel etc)

Many thanks,

Sam

 

(I would like to share a discovery of angle technique: I often see the lament of wire wheels getting clogged with bitumen, or making it too hot and smearing it. I've found it quite effective to hold the grinder so its practically tickling the bitumen, or tap it lightly... it takes it off really quickly. Also best to only spend a few seconds per patch so it doesnt get too hot, and of course better to do on a cool day. Also, after a few minutes, where even the tapping is simply smearing... have a scrap of metal near by and periodically clean the grinder with it. I have been using the same wire wheel on many metres of bitumen with this method. Also, I have seen warnings of taking off the good metal: if you are gentle enough, you will see minimal sparks.. at least with the top layer of bitumen there will hardly any sparks at all, but being observant of what splatters out of the grinder is a way to keep metal loss to a minimum... hope this is helpful to someone..!)

 

IMG_20170918_154330.jpg

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I don't really know a lot about stopping it getting worse,but if that lot was on a transit van chassis  or in the bottom of my boat,I'd either wax oil it or spray a load of waste oil  and diesel mix  on it ,it soaks in everywhere,I might be wrong ,but I recon all paint will do is seal in the rust already in it and Itl still keep rusting,  there's one thing for sure ,my two methods stand more chance of stopping further corrosion ,well  only till some one can convince me otherwise

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Eep.... :( well, the welder says he hasnt had a boat sink yet....maybe mine will be a first. Its really old (at least 30-40 years) steel and he kept blowing through... and all the bitumen bubbled. Dunno.... could grind it back and weld it again? Cant afford to pay someone.... been learning, but have hardly done my mile of weld. 

Painting over grease or diesel sounds a challenge too..!

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59 minutes ago, abnormalsheep said:

Eep.... :( well, the welder says he hasnt had a boat sink yet....maybe mine will be a first. Its really old (at least 30-40 years) steel and he kept blowing through... and all the bitumen bubbled. Dunno.... could grind it back and weld it again? Cant afford to pay someone.... been learning, but have hardly done my mile of weld. 

Painting over grease or diesel sounds a challenge too..!

This shouldn't be complicated.

Assuming you aren't after a pristine paint job there is no need to remove soundly adhered paint prior to repainting (welding is a different matter though :unsure:). Remove as much visible rust as you can mechanically and then use a rust treatment (which is phosphoric acid based not acetic acid like vinegar) to convert the remaining bits that will sit in small pits and difficult to access areas. There is no miracle cure that you can paint over rust successfully.

Basic corrosion prevention starts with keeping things clean and dry and even without repainting that will help. It's also the first part of preparing the surface for painting as you will need to have a clean, dry and de-greased surface on which to paint. I think vinegar will clean the surfaces but not sure about de-greasing. Take the worst stuff off with rags and then wipe down with super soap solution. It doesn't look too bad on your photos.

I am not aware of any reason you shouldn't use the MIO paint but it may be worth confirming what it ideally should (or perhaps shouldn't) be overpainted on if possible. It's protective abilities come from the internal particle structure (that's the 'micaceous' bit). As you are probably aware the colour range of MIO is basically 50 shades of grey with an industrial finish so on the inside surfaces of the hull seems as good a place as any to put it. You don't need a bituminous paint there.

And lastly I had to chuckle at Crow's description of the weld. Fingers crossed it's watertight.

JP

Edited by Captain Pegg
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Thanks JP for your effort of simplifying something I was making a little too complicated! 

Will go forward with the vinegar & soap washes. Will probably use a hair dryer to make sure moisture doesnt linger! 

Found an MIO data sheet last night that went into detail about different surfaces, including painted surfaces, so I am a bit more reassured now! As it was a gift I had no idea about it... but having successfully found routes of reading... it seems to be used in external paint too, and is actually pretty pricey at £80/5 litres. So now im wondering about using the red oxide I have for the inside, and the MIO on the outside, as an intermediate layer between some zinc stuff and top coat. 

Just as I felt a little certainty another possibility raises its head..!!?

Either way, the uncertainty of how much paint to remove inside has been reassured!

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2 hours ago, abnormalsheep said:

Thanks JP for your effort of simplifying something I was making a little too complicated! 

Will go forward with the vinegar & soap washes. Will probably use a hair dryer to make sure moisture doesnt linger! 

Found an MIO data sheet last night that went into detail about different surfaces, including painted surfaces, so I am a bit more reassured now! As it was a gift I had no idea about it... but having successfully found routes of reading... it seems to be used in external paint too, and is actually pretty pricey at £80/5 litres. So now im wondering about using the red oxide I have for the inside, and the MIO on the outside, as an intermediate layer between some zinc stuff and top coat. 

Just as I felt a little certainty another possibility raises its head..!!?

Either way, the uncertainty of how much paint to remove inside has been reassured!

 

1 hour ago, abnormalsheep said:

I suppose its still better to use inside, as there is perhaps a stronger need for the anti corrosive properties, with the constant condensation? 

The inside of the hull is arguably a more harsh environment than the outside - at least below the waterline - hence it pays to keep it protected. If you are painting the outside of the hull you ideally want a nicer finish than MIO will give. MIO is a paint system for industrial steel applications. Until about 25 years ago bridges were painted with it and they were all matt grey. It's no longer state of the art for new build so bridges are more aesthetically pleasing these days. It isn't anti-corrosive per se. All paints (top coats anyway) will protect against rust providing the surface is properly prepared and paint coverage is good and undamaged. MIO will resist damage hence seems like a good option for the inside of the hull.

JP

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Hehe yaay.. thank you JP.. is amazing what a bit of concurrence does!

Dont mind too much about appearances on the outside, as will probably put on a bitumous top coat anyway..... and i'll probably use a primer that would be sufficient for the outside. Can also be grinded back or shot blasted much easier than the inside, once all interior is in. 

So, now it seems absolutely clear, that it is best to invest the MIO for the inners.

Sweet!

Thanks again ^_^

 

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