'Pausing' Rust

Good old fashioned HCl

Apply/inject with phosphoric acid - it has the consistency similar to water.

Phosphoric acid is a rust "converter" in that it turns iron oxide (or rust) into ferric phosphate, a black coating.

Example product

My experience is these bubbles are caused by perforation, and best left alone.

Restoration should be remove and replace the affected area or replace the panel. I guess it depends on how bad it is?

Rust bubbles are usually caused by the metal rusting through from the other side then spreading along underneath the paint. Only real way to stop this getting much worse short term is to spray the reverse side with wax, etc. But usually by the time a bubble appears the corrosion can be extensive. I've seen one wheel arch which only showed one small bubble. But on sanding down to bare metal showed corrosion starting all around the arch. It is heart breaking to make a decent repair of what appears to be a local problem, only to have rust break out a few inches away in short order.

Yes, it's really not possible to fully evaluate the extent of any such corrosion without totally stripping the body down to bare metal. :(

I'm just looking for a stop-gap solution to buy me a a few more months.

In message , Fredxxx writes

We had a Triumph Toledo. I spent many unhappy hours trying to deal with rust under paint bubbles. Just about the time I got rid, someone said to me "Didn't you know that the Triumph Speke plant was close to an acid factory and the cars were often parked outside in primer during the frequent strikes? When it rained it rained acid droplets".

The rusting was quite different from that on the Commer caravanette, which rusted primarily from the inside.

Someone familiar with the model can usually make an educated guess how far the corrosion has spread after it starts showing.

I don't do bodywork (can't weld thin stuff) and used a recommended repairer to fit a new rear wing skin on the SD1. His website showed some superb award winning work, but on Triumphs rather than the SD1.

I'd had the other wing replaced some time ago by a local firm no longer in existance, and assumed he'd do it the same way. Even gave him a copy of the instructions from the BL WS manual.

But he decided to save time by cutting a repair section from the new panel. Not only did the join show, but he'd not replaced all of the bits of the panel that rust. Ended up having to get another new panel (not easy) and have the job done properly.

Not sure a few months will make much difference. But providing holes to spray the back of the panel with rust inhibitor and wax can save having to do this once the repair is done properly. Except that the wax etc will need cleaning off before welding.

Regularly spray with WD-40?

The WD stands for Water Displacement ye know.

I'll get me goat...

As has been suggested, it's probably best tackled from behind (if possible). Remove thick dirt, and spray behind every so often with good old WD - at least initially as it may penetrate better than less-fluid wax.

Much more expensive than WD40, but Dinitrol do a thin penetrating rust fluid for older cars. Used before applying wax. It's said to creep into seams, etc.

In message , "Dave Plowman (News)" writes

WD40 also creeps well. It's main advantage is that nearly every DIYer* has a can somewhere about the house.

*Except for the infidels who don't believe it does anything it says on the can.

The problem with WD40 is many people also think it's a penetrating oil for thread release. At best it provides a path that can wick up a proper graphite oil.

I was amazed when a tyre fitter sprayed some around a stuck on alloy wheel, he went away and changed the other tyre, came back to the stuck one and just lifted the wheel away.

Well, it is - but maybe it's not as good as product specifically designed for that purpose (like, say, Dinitrol penetrating oil is).

I've certainly tried to stop further rusting by first applying several sprayings of WD40 (allowing each spraying to soak in), and then using Waxoyl (more permanent).

It makes a good cutting fluid for turning aluminium on a lathe at least.

It's a VERY expensive way of buying kerosene

Having sprayed it on things like garden gate hinges, I can confirm it doesn't keep rust at bay for long. ;-)

Screwfix do a 750ml Penetrating/Lubricating Oil a lot cheaper and seems to be just as good if you need a spray can

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In message , "Dave Plowman (News)" writes

Used outside, rain will wash it off - although usually it lasts a bit longer if the solvent is allowed to evaporate before it rains.