Waxoyl or bitumen based underseal?

[C.J.]

Moggsy is going in for a full rust removal , body repair and re-spray at my local classic car renovator specialist in April, and he's talking about a specific type of underseal, the name that slips my memory presently.
I always though clear waxoyl was the favourite, as it gets into places that underseal cannot, especially if warmed up first?.

What's the general opinion on this sticky subject please?

[DAVIDMCCULLOUGH]

Ive used dynax 50 the last few times, much easier to apply than waxoyl as it comes in big aerosols with extension probes.

http://www.opieoils.co.uk/p-73830-bilt- ... n-wax.aspx

I havent tried there brush on underseal yet, a friend has bought it for his car though so Ill see what its like.

Ive also used hammerite underseal with waxoyl added and find it good stuff, even on the car thats used summer and winter.

http://www.amazon.co.uk/Hammerite-50929 ... =underseal

[C.J.]

I worry about rust being 'sealed' in, or do these products actually halt it from getting worse and spreading?

Remember those little bottles of 'Kurust'' that we used to brush on, the manufacturers claiming that it actually KILLED rust?

I can't reasonably expect every single last trace of rust being removed during renovation, unless I want to pay many more thousands to have an entire strip down.

[Redmoggy]

If it's going in for restoration why can you not reasonably expect all the rust to be removed?

No under seal will kill rust or stop it from spreading. Your first step after removing the original finish should be to remove the rust by which ever means you decide is best. You can use power tools, wire brushes, blasting media or chemical stripping. Once all the rust is gone and repairs made a rust inhibiting primer should be applied and keyed before all seams are sealed with a purpose made seam sealer. The surface can then be primed and your chosen under seal applied. For my money I prefer stone chip, never been a fan of the thick bitumen based products they make it far to easy to hide poor quality repairs. Stone chip can also be painted over with most automotive finishes offering even more protection.

After that the best rust prevention is keeping the thing clean and not allowing mud and moisture to build up in corners and crevices.

Regards
Rod

[graham1957]

i agree with rod,clean off to bare metal,treat any pitted rust with rust converter,zinc prime {electrox} from bilt hamber,then seam seal, then gravitex stone chip two to three coats and then colour paint. Box sections, chassis legs,screen pillars, boot lid and sills and any other cavaties use bilt hamber dynex s50 aerosol with supplied tube.
The zinc primmer can be brushed on and into seams.The gravitex needs a cheap compressor about 100 quid and shultz gun about 15 quid. The stone chip is thick enough to cover the brush marks.hope this helps ,Graham

[dewaraj]

I discovered AQUASTEEL a few years ago, it is a corrosion control system developed by Bayer-Wood Technologies for use on rusted metal surfaces and supplied by Aquamarine. It is water based and solvent free. I treated my Defender 90 chassis, my Morris Minor and numerous other items with excellent results and find it long lasting. It is used to treat oil rigs, yachts, etc. so if good in those environments must be good stuff!!!. I also use Teroson Terotex Super 3000 stone chip on top of treated areas, neither are cheap but if you want a long lasting treatment it is worth it.
AQUASTEEL can now be purchased on amazon and is slightly cheaper than buying direct from Aqua Marine.

[panky]

I can second that great on old rusty stuff that's been cleaned off, but it's no use what so ever on new metal as it doesn't adhere to the surface. I usually get it off Ebay where it's cheaper than buying direct.

[andypocock]

I like the Dynax for inside box sections but good old Waxoyl takes some beating outside. I'm still finding bits of it on a Moto Guzzi that had been treated before I bought it 35 years ago. I've been trying to get rid of the stuff ever since.

Main piece of advice I have is that rust proofing is not a fit and forget part. You need to check it once a year and top up / repair as required.

[midget]

Very timely subject for me, as I have just finished a load of welding to my 2door rear inner wing and surrounding area. Am not familiar with seam seal, but have bought some Frosts to apply to all the welds.
However, is it acceptable to use this sealer on the outside surfaces to be painted? Will it not be compatible with primer and topcoat? I had to extend the body around the wing repair flange as the pattern parts would not reach.[frame][/frame]

[bmcecosse]

It's not for any area that is externally painted. Just for seams.

[Redmoggy]

Whilst seam sealer can be painted over it should not be used under body filler. In your case I think I would be skimming the repaired rear quarter and sanding to shape first.

Regards
Rod

[midget]

Thanks for feedback and I'm not arguing as I genuinely dont know,but--when used on the underside/inner wing areas etc, it is then coated with primer and then stone chip/underseal. What is the difference when using top coat? does it shrink/expand with temperature differences, causing damaged paint finish? It will of course have a fair amount of body filler applied on top of the welded/sealed area.
I am keen to ensure that this area does not need my attention in the future as it has been an arduous time consuming task.

[Mark Wilson]

I'm watching this one with interest as well. I've seam sealed all my "hidden" welding, and will do the same when I come to paint the underside. I intended to use a modest amount of filler to blend in the inner wing repairs, as Rod has suggested - but when I mentioned this in a previous thread hands were raised in horror, and I was told that seam sealer is the only acceptable finish for welds in this sort of area. .Hmm...

The main problem with seam sealer is that it tends to provide a very lumpy finish. One tip I came across but haven't tested yet, is to dip your finger in thinners to smooth it off.

Mark

[Redmoggy]

Seam sealer is not a suitable base for body filler, it simply will not adhere to it and the repair will fail. Therefore if you have welded repairs to external bodywork like the section just above the rear wing mounting flange, this should be sealed from the inside after priming the bare steel. The outside should be filled and blended into the mounting flange before priming and adding seam sealer to the seams.

Hope that makes sense?

Rod

[Redmoggy]

Mark, the only issue with applying body filler over a weld is if the join is porous. Moisture will then set in and lift the filler. Hence why I mentioned sealing the repair from inside.

Rod

[Mark Wilson]

Thanks Rod. I've only the usual small areas at the bottom of the front arches where this is an issue, but the inside face isn't fully accessible. I think I'll follow some earlier advice and seal any potential pin holes with JB Weld to avoid porosity, then fill and sand over bare metal before priming, stone chip and top coat.

Mark

[trabant]

I would never ever use stonechip (gravitex) on anything water and therefore rust has a lovely habbit of creeping under it the same goes for bitumen or rubber based undeseals. Underseal is what you slap on old escorts to get them through an Mot not a long term solution. If the car is going back to bare metal a light coat of upol etch primer copious amounts of zinc primer ive found upol zinc 182 is as good as any and cheap enough top coat that ( I.e body colour) then clear waxoyl the lot. That way if something breaks the paint layer the waxoyl should have enough creep in it to keep moisture at bay and you'll be able to see and treat anywhere it hasn't. As an add on to that if a body shop is doing the work get the underside top coated.in 2k paint not cellulose its much more chip resistant.

[trabant]

On the subject of seam sealer if you want to be really fancy both 3M and Upol manufacture a sprayable seam sealer in its own special bag this gives you the finish you get on seams in modern cars and is over paintable the stuff in gun cartridges is pointless tat.

[Mark Wilson]

Totally agree on underseal, horrible stuff. Stonechip, though, I thought would improve the chances of avoiding rust by protecting the primer and undercoat from chipping in the first place. Obviously would need regular inspection and maintenance. I'm not speaking from experience, though. Have you experienced problems with stonechip?

[trabant]

Stonechip is quite rubbery hence its ability to be bash resistant when it ages is has a tendency to crack in places and then you've got water and rust creeping away under it. Seam sealer often has the same effect if you look at modern motors in the scrapyard you will often find the seams are the most rotten part. Basically anything like that will when it fails hold water to the metal which is exactly what you don't want. I just do what I've mentioned above and keep on top of it when fitting wings the flanges get waxoyled before fitting and the same with door hinges etc.
I have in the past used a product called raptor which is made by Upol and is a sprayable pick up truck liner its available in either black or a colour tintable version to match body colour. This stuff is rather good its stopped a Lancia beta from rusting so it must be.