Overpainting Rust

[Drago]

Bilt Hamber DeOx and DeOx gel. Pricy, but it works totally.

 

[Pale Rider]

[QUOTE 4018504, member: 9609"]
The acid in our stomachs is surprisingly powerful stuff, vomit will damage paintwork.[/QUOTE]

It will.

A friend of mine was sick down the passenger door of my car after a lager and curry fest.

Better than being sick inside the car, but the vomit left a bloom on the paintwork which I could never fully remove.

 

[Deleted member 23692]

White vinegar does a nice job on small parts, but creates a dark precipitate that then needs to be cleaned off.

The method I read said after the vinegar's done It's work, rinse off and then leave the part in a sodium bicarb solution for a hour or two. this allegedly stops the reaction. I've no idea if it did or not, but it left a dark grey slime which washed off quite easily. This left a dull grey surface on the part which seems to resist rusting.

 

[Gravity Aided]

I like the idea of a bicarb bath, I'll have to try that. Bicarb or calcium might do a good job of neutralizing the acids, but I sometimes also use the coca cola and aluminum foil method, which deposits a shiny layer on the oxidized surface. I will also try chrome polish from time to time. As my blog of last week shows, there are immense conical barns in my area. This is where the salt for the roads is kept. So I see a lot of rust on the bikes that commuters use every year. The bicarb may be a better solution for some of those bicycles.

 

[Illaveago]

[QUOTE "Katherine, post: 4018979, member: 36653"]In terms of prevention :
My husband has insisted that I wipe the underneath of my bike with oil to stop it rusting over the winter. Has he got any good reason for this? Will my bike really rust underneath without the oil?[/QUOTE]
It won't do any harm and it may prevent rusting. I was told many ,many years ago that all paint is porous.

 

[Gravity Aided]

[QUOTE "Katherine, post: 4018979, member: 36653"]In terms of prevention :
My husband has insisted that I wipe the underneath of my bike with oil to stop it rusting over the winter. Has he got any good reason for this? Will my bike really rust underneath without the oil?

It won't do any harm and it may prevent rusting. I was told many ,many years ago that all paint is porous.[/QUOTE]
I usually use a heroic amount of wax on the bottom of the bicycle, which keeps mulberries from sticking to it in spring, dirt and road tar from sticking to it in the summer, and leaf bits from sticking to it in the fall, as well as snow, ice, and salt in winter. A four seasons approach.

 

[Gravity Aided]

As you're north of the border why aren't you using white stuff anyway?

I thought it was just Canada did that. Shocker for me, used to malt in the States.

 

[Profpointy]

if i remember my chemistry, phosphoric acid actually changes the rust into a less problematic material (can't now remember if it's iron phosphate, or a different oxide of iron). The problem with rust is that it flakes off exposing the iron underneath - unlike alumium oxide which forms an impervious skin, or some of the other forms of iron oxide which are akin to "blued" steel). Thus phosphoric acid to a degree "treats" rust, not merely removing it.

Hydrochloric acid may remove rust to an extent but will also attack the steel itself and the resultant iron chloride is itself water soluble. Ferric chloride in particular is quite corrosive in water and will dissolve copper (I never understood the chemistry of that but it is used to etch copper circuit boards)

 

[Smokin Joe]

[QUOTE="Illaveago, post: 4019217, member: 44077
It won't do any harm and it may prevent rusting. I was told many ,many years ago that all paint is porous.[/QUOTE]

Who told you that? The paint on my 1999 Astra doesn't appear to be as it's rust free.

 

[RichardB]

In terms of prevention :
My husband has insisted that I wipe the underneath of my bike with oil to stop it rusting over the winter. Has he got any good reason for this? Will my bike really rust underneath without the oil?

More usual for cars, where its a great bit of advice, but bikes don't have the hidden corners where rust can develop unseen. If you keep it clean and tackle any corrosion when you find it, you should be ok. My motorbikes lived outside all year round, and I just washed them once a week and sprayed the frames with WD-40. They seemed to stay looking good. I'm doing the same with my commuter bicycle and it's fine. Oil is messy and heavy, but WD-40 is easy to apply and smells nice. Keeps the worst off.

 

[Illaveago]

[QUOTE="Illaveago, post: 4019217, member: 44077
It won't do any harm and it may prevent rusting. I was told many ,many years ago that all paint is porous.

Who told you that? The paint on my 1999 Astra doesn't appear to be as it's rust free.[/QUOTE]
TROWBRIDGE COLLEGE City & Guilds Painting and Industrial Finishing course. 1971 to 1973. There have been major changes in the construction of motor vehicles especially in the rust proofing area . A lot of the steel panels have a thin zinc coating, the lower portion on the body has a rubberised stone chip coating, and a lot of the internal body work has wax injected into it.

 

[Drago]

That Astra is made from galvanised base stock. The edges are exposed steel from when the panel shapes are cut, but as you say they take care of this well with waxy injections etc. You really have to abuse a modern car, never clean it, ignore stonechips and scrapes, to get it to start corroding inside a decade.

WD40 is a poor anti corrosion spray. ZX54 or ACF 50 are much much better, developed as they were for the Fleet Air Arm to prevent turbine blade from corroding at sea.

 

[Illaveago]

If people are worried about their cycles rusting from the inside out they could always spray something like waxoil down inside the frame. It is runny to begin with, gets every where but it eventually turns into a wax.

 

[Drago]

Dynax is much better than waxoyl and comes with a lance that's ideal for injection into drain tubes.

 

[RichardB]

That Astra is made from galvanised base stock. The edges are exposed steel from when the panel shapes are cut, but as you say they take care of this well with waxy injections etc. You really have to abuse a modern car, never clean it, ignore stonechips and scrapes, to get it to start corroding inside a decade.

WD40 is a poor anti corrosion spray. ZX54 or ACF 50 are much much better, developed as they were for the Fleet Air Arm to prevent turbine blade from corroding at sea.

I wouldn't recommend WD-40 for a permanent protective coating. But it's very good at chasing water off a cleaned surface and leaving a thin oily coating. Applied weekly, it keeps the worst at bay. And it's easy with no mess.