Classic and vintage specials.

Sympathetic conservation, preservation and longevity

 in refinishing and spray painting of classic and vintage vehicles.

Structural and panel refabrication.




Alchemy:  The ancient study to seek out a way of changing base metals into gold.

Met-alchemy:  The modern art of turning a basically rusty car into a valuable classic.

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Beating the Tin Worm

I studied Chemistry in school.  I did it to A Level standard. It was my favourite subject for many years.  Over the years, although it has not been of everyday significance, every now and then something pops up in the grey matter.

 This time it is the pertinent fact that Iron or steel rusts in the presence of moisture and oxygen.  Take one or the other of these away and no rusting occurs.  This is because while rust is Iron Oxide, Iron and Oxygen don't just spontaneously combine.  If they did, we couldn't use steel for anything as it would soon degenerate into crunchy Bran Flakes, food for the Iron Chicken, even indoors or in the desert!

 In water with no dissolved oxygen, Iron can't combine with the oxygen in water because that oxygen is already attached to the Hydrogen elements which make up water itself and it won't give that happy bond up lightly, as Hydrogen and Oxygen like each other very much, as the Hindenburg air ship very ably demonstrated!  Hydrogen and oxygen can spontaneously combine - explosively, unlike iron.  It's just as well!

In water, however, Iron does dissolve to a certain degree, as most things do, its atoms forming"Ions", by losing electrons, so becoming positively charged.  Dissolved oxygen in water, (as opposed to that oxygen with makes up water), ionises too, by attracting electrons, making them negatively charged.  In fact, the Iron's tendency to lose electrons feeds oxygen's tendency to attract them, and so the two join themselves together, forming a very happy bond, like finding the right girl to marry, and they become inseparable.  Hence the formation of Iron Oxide, curse of the classic car owner, but gold dust for the restorer's pocket!!!


So what can we do about it?

Traditionally, painting has, for always and always, been the solution to keeping rust at bay.  On areas not normally seen, or easily paintable or maintainable, oil spray has been traditional.  These solutions do actually work, by excluding both air and moisture; moisture being the most important one due to its dissolved oxygen content.

 Why then do we have problems?

Cars almost always rust from the inside, not from the outside, and this is because of the lack of proper treatment given to the inside of panels in the manufacturing process of older cars.  Much later on, phosporetic dipping treatments and galvanising has revolutionised car body life, and nowadays it is more likely to be built in obsolescence of other descriptions, (like lack of availability of spares, unmaintainable electonic gadgetry, and the continual emergence of new model shapes), that ensure early demise.

 Anyway we are here to talk about how we beat the tin worm in our beloved older cars which were never really protected properly due to the lack of internal treatment.

As we know, various waxes have been developed which purport to coat existing rust and ensure that it is sealed from the atmosphere.  Some of these are available at most motorist outlets and the cheaper ones are rubbish as they don't last, going hard and flaky.  Also, coverage is important and how do you tell if all your box sections are properly covered inside?

One of the best treatments is still Shell Ensis R or S, which has been available for years, but is an industrial dewatering and preserving fluid so is only available in larger drums from Shell oil dealers. It has to be good as it is an industrial product and in industry they don't mess about.  If it didn't work, they'd junk it.

Of those available to the classic owner, Dinitrol or Dynax S50 are the best, and well worth the extra outlay.

I did experiment with Rust Encapsulator, but reference to my MG pages will show that I was not impressed as while it stuck to the rust, it doesn't stick to bare steel or paint, so what are we supposed to do at the edges?  Instead I encapsulate in paint and other stuff!

These waxes and indeed, 3 in 1 oil if you can get it in big cans, are fine treatments for the insides of box sections and those hard to reach areas, and oil will penetrate seams better than any wax, but on areas which are paintable, they are not a good substitute.  They can degrade with abrasion etc. and despite their creeping powers, they still need regular recoating to ensure coverage is not interrupted.  Therefore they are not for use on bare steel only.

Paint followed by wax coating is generally seen as the best option

So why do we still have problems even when our restoration is complete?

So you have paid several thousand pounds at your chosen restorer and are very pleased with your gleaming treasured posession when you drive it back home.  You top up the wax coating underneath every couple of years, but as it's a right pain to do properly, inevitably full coverage isn't achieved.  The new metal which was installed may not have been painted on the inside, or even on the outside when underneath, so when the wax coating breaks down, rust sets in quickly.  It doesn't have to be in the rain to get wet either.  Condensation forming inside every cavity  and internal surface on a day when the weather changes from cold and dry to warm and wet, will do more damage than any amount of rain running off the outside.

Then eventually you notice that bits of metal which were repaired, either by weld repairing or rubbing out surface rusting, and repainting, start to break out again.  It brings one to tears.  Back to the restorer's for some conservation and round the circle goes again.

 While it is very hard without industrial facilities and a total shell strip down, to fully treat with anything really effective totally comprehensively, we can, by attending to detail, cut out all of the main causes of premature rusting on our restorations.  By no means all of these are attended to by all restorers, some of whom consider that a skin deep beauty is all that will be required!

 One very basic requirement is that rusty panels or sections full of holes and pits,  which have been marked for replacement, have to be replaced by metal the same size as that cut out.  Overlapping of welded panels is the most effective way of making sure that it will not last any time at all.  Butt welding joints is basic.  While the outside may be sealed over with filler skim etc, it will soon rust through again from inside, worse than it was originally due to the newly installed moisture traps. 

The other thing is to ensure that when these new sections are installed, they are properly sealed against moisture entering from the inside as well as the finished outside.  These new welds and all the inside faces have to be protected to avoid moisture transference to the outer face of the new panel, apart from the inner face.  Seam welding will be proof, but plug welds replicating original spot welded joints will need sealing up so as not to merely replicate original style rust traps.

Apart from the problem of corrosion being accelerated due to electrolysis in the presence of dissimilar metals, (body steel and welding metal leading to the battery effect which is present with all dissimilar metals, which includes different grades of steel, the severity of which is dependent upon the metals' positions in the Periodic Table, and is why aluminium, which oxidises when next to steel in moist environments, falls apart far quicker when in the presence of stainless steel, contrary to popular assumption), there is the added problem of the surface roughness and problem of coverage with any sort of coating.

What is not generally appreciated is that :

paint is not particulary good at keeping out moisture.

Keep that in mind at all times.  This is especially true when painting over rough surfaces like ground down welds and panel edges.  Paint looks like it has coated really nicely, but actually all those sharp points on the surface, microscopic in size so you can't see them, tend to break through the surface layers very easily, exposing microscopic areas of bare steel to the elements.  It's a death timebomb ticking away.

This is the trouble with painting over rust.  It isn't that rust, when in the metal, can't be stopped, as is the popular opinion.  It can be stopped in its tracks, with the exclusion of moisture and oxygen.  Oil coating shows this admirably because oil seals out moisture, until it breaks down!  The thing is that a few coats of High Street rust treatment paint, or indeed a few coats of cellulose primer and top coat will not seal out the moisture.  Both because of the rough surface as explained above, and because paint does pass moisture anyway!  Only building up lots of layers and using epoxy paints, which are naturally more moisture resistant, can combat this, and with rougher surfaces, this will quckly become impractical.

How then do we get over the problem?  It is very difficult, or indeed nearly impossible to guarantee eradication or total encapsulation of rust, although actually I think that over 90% of the problem can be overcome by the use of proper well chosen paints (paints with the best moisture resistance and coverage / filling properties), fillers to smooth out rough areas prior to painting, primers which also provide an ultimate moisture barrier, with filling properties, and after coatings which protect the paint surface and further sealing of edges against exposure.  In that lot somewhere is the sealing up of overlapping joints such as spot welded panels together with folded over joints of bare uncoated steel, such as those found on door skin to frame joints, famous for their bulging out with rust, due to moisture running straight into them inside the doors.  These seams should be filled with sealer and painted over inside. Attention to detail and determination to make a job the best it can be are the biggest key points in our search for longevity and there is no reason why a car should not be given a very extended life span by careful detailing!

I have spent quite a long time deliberating and experimenting with different types of industrial paints, for use in unseen areas, none of which are available in the High Street due to solvent regulations, and much more time in ensuring that the places that need to be treated actually are, by some means, treated as best as possible, and with something meaningful.  All this is in the unseen areas, and much of the conclusions are explained in the MG V8 pages.

I haven't even spoken about top side refinishing yet, but this pales into insignificance when you read the following:

Basically I am horrified at the standard turned out by some restorers who are supposed to be "professional".  New arch rings installed with no internal treatment at all, butting up to old inner arches and not even attached.  Rear valance / wing corner pieces repaired three times, each new steel layer being applied to the former one, and each so rusty that they can be peeled back one by one from inside, eventually leaving a quarter inch thickness of filler hanging in mid air still looking lovely from outside but attached to a doiley in steel and rust at the back!  And that after only about ten years!  Floor panels installed new and coated only with back waxoyl, rustier than the remaining original thirty four year old floor sections after only ten years of installation!  Not good, but very typical.


Now at last, for the paint!


To put things in perspective, the top sides can be summed up in one paragraph... two pack filler primer in about half a dozen layers followed by a similar number of layers of cellulose filler primer, each sanded down to achieve a perfect level finish, and this topped off with another half a dozen coats of cellulose colour. Job done.  Two pack primer provides a plastic layer giving good moisture resistance, especially in depth, while the cellulose top coats provide that quality of finish which you will want on your classic!


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