Question about rust treatment

[jonathanA]

8 hours ago, john.k said:

If you seal over rust ,you will likely accelerate the rate of rusting and failure.............the simplest effective way of removing rust from steel is flame spalling ,followed by light wire brushing and a vacuum cleaner 

Really ?  I always understood rust needed Iron, Water and Oxygen, take away any one and no rust. so sealing rust can't accelerate it  can it ?

 

what is 'flame spalling' ?

[MtB]

2 minutes ago, jonathanA said:

what is 'flame spalling' ?

 

Might it be where you get a flame, and spall with it?

 

More seriously, I wondered too.

 

Also agree with you about the rust!

[jonathanA]

google says :

spalling is a term used to describe the process that occurs when flakes are separated from some type of larger body of material. The separation can be caused by many different factors, including the natural process of weathering, corrosion, continual friction, or a direct impact with another object. Many materials used in machinery are subject to some degree of spalling, as well as many types of building material.

 

seems to be lots of references to concrete spalling but can't see anything for flame spalling and can't see how heating up rusty metal will clean up rust - other than drying it out making it easier to seal it... 

[Tonka]

1 minute ago, jonathanA said:

google says :

spalling is a term used to describe the process that occurs when flakes are separated from some type of larger body of material. The separation can be caused by many different factors, including the natural process of weathering, corrosion, continual friction, or a direct impact with another object. Many materials used in machinery are subject to some degree of spalling, as well as many types of building material.

 

seems to be lots of references to concrete spalling but can't see anything for flame spalling and can't see how heating up rusty metal will clean up rust - other than drying it out making it easier to seal it... 

You get bricks that have spalled if you use the wrong mortar to point them

[Alan de Enfield]

11 minutes ago, jonathanA said:

Really ?  I always understood rust needed Iron, Water and Oxygen, take away any one and no rust. so sealing rust can't accelerate it  can it ?

 

But those little MIC critters that cause corrosion are anaerobic and thrive under paint steadily eating away the steel until all that keeps the water out is the layer of paint.

[cuthound]

3 hours ago, MtB said:

 

And steel from 20 years ago was better. Always has been. I remember being assured of this back in 1977.

 

Last time I used Danboline is seemed (and smelled!) the same as it ever was. 

 

 

 

I recently did the sides of the engine hole and bow lockers with Danboline (I got a local painter to do the baseplate area for me as I am no longer flexible enough to reach them).

 

As you say it seems the same as always.

 

The proof will be in how long it lasts. The original lasted about 15 years before the rust began to appear, although my bilges are usually bone dry thanks to the cutlass type prop bearing.

 

I will be really happy if it lasts that long as I think I will.have given up.boatibg on age grounds by then 

[ditchcrawler]

3 hours ago, MtB said:

 

And steel from 20 years ago was better. Always has been. I remember being assured of this back in 1977.

 

 

 

 

And I bet the chap that told you had been boating 30 years

[Mike Adams]

I have found that the best solution for bilges that don't have easy access is to get some antiroest grease which I think comes from Holland. Heat in up a saucepan and apply by brush.A few millimeters thick coating seems to stop it completely. Also you just need to remove any loose material first but as has been said you need a lot of scale on the inside to much of steel but you can get pits. You can get it online if you search. No use where you have oil or diesel in an engine bay but in the rest of the bottom seems to be fine.

[Peanut]

Laser spalling:

 

 

Read all about it on their website. Costly to buy.

Edited August 29, 2023 by Peanut
cost

[ditchcrawler]

I have just had this pop up as an advert RustBullet | RUST INHIBITIVE COATING (rustbulletuk.com)

[john.k]

Laser cleaning uses the same principle as flame spalling .....rust doesnt conduct heat ,and becomes white hot almost instaneously ,turning into a powder,the larger scabs exploding off ............rust is a water bound compound , this is why sealing rust doesnt stop the rust ,it simply changes the chemical process slightly........but it does hide the rust for a while ,until scabs form under the coating ,cracking it off.