vactan

[Oldjets]

Out of interest, I painted a test strip last July (2009) with Vactan and various paints and left it outside to see what happened. Hopefully photos have loaded and will show results

Steel was an 1.2 mm offcut with very light surface rust. It was wire brushed and degreased.
All paints and coatings were allowed to dry before applying any further coats. Didn't take too much trouble over finish, so edges are a bit ragged. First photo one shows mild steel test sheet freshly painted:
1 - Vactan straight on to steel
2 - Vactan +Zinc 182 primer + white Rustoleum
3 - Vantan +Zinc 182 primer + Manor Coatings chassis black
4 - Vactan +white Rustoleum
5 - Vactan +Manor Coatings chassis black
6 - Rustoleum straight onto steel
7 - Chassis black straight onto steel

Second and third shots show how things look after 8 months weathering.

Biggest surprise for me was the Vactan with no other coating on top. This weathered pretty well and is only now beginning to bubble up with rust forming underneath. The other sections look ok with a little rust coming in from edges on all of them. So far having a primer under the topcoat is not making too much of a difference. Section 5 is a bit worse at the edges, but to be fair, some paint chipped away right after application here. The chassis black seems to be a bit easier to chip - both it and Rustoleum are very hard paints, but go on well.

Not very scientific, but I will be leaving the test piece out for a bit longer to see what goes first.

Vactan seems to be good on lightly rusted metal and I have been brushing it into seams and over rusted parts before painting with good results so far. Thin coats work best giving a nice black finish. Putting it on too thickly seems to cause it to peel off when dry. It also doesn't mind a slightly damp surface, although I don't think I would brush it into wet panel seams.

Hope that is of some use.

[CovKid]

Pretty much what I found Oldjets. Rustoleum straight over Vactan works very well indeed unless rot is excessive or its an area you're not getting full penetration like seams (ie you can't get in fully from both sides) but that applies to any rust treatment. The exclusion of oxygen is a big part of dealing with it.

I tested Vactan on a mate's narrowboat at Coventry canal basin, painting a tow hitch with vactan only and it held its own for a couple of years. I guess everyone has their own preferred way of dealing with light surface rust, but Vactan seems to be the least toxic and trickles into small crevices well.

Chickenkoop is driving around with only Vactan on his rust spots and has been for some months, and it seems to be keeping it in check until he can get around to painting his whole camper. The reality is that you can't really stop panels sucumbing to rust in the longer term as it only needs a nick in the paint (whether hidden or not) to spread, but Vactan does seem to stop it on minor areas and severely slows it down on more major areas. I had a more rusty area close to my petrol filler that came back despite the use of Vactan but I'm fairly sure all the real damage is happening from behind so a panel replacement is a better option in situations like that.

Minor stone dings and surface stuff is easily dealt with although scoring up the surface to get as much bright steel as possible is wise. I certainly wouldn't bother say vactaning a hole and then filling. That won't last long at all and it would be preferable to cut out the rot entirely.