Stopping your pride and joy from turning into a pile of flakey brown stuff is one of the highest priorities for most old car owners. Any Datsun owner knows how rapidly these cars can rust if neglected. There are dozens of different products on the market which are aimed at tackling the never ending rust problem but how effective are they? I thought I’d try to find out…
Some kind of real world test was needed to find out just how effective various types of product are. You’ll notice I said ‘type’ of product rather than ‘brand’. That’s because what I am looking at here is which type of treatment adheres best and resists corrosion for longest. There are several different types of products to try… paints and primers, wax based coatings, rubberised underseals and even specialist rust conversion coatings, so I’ve chosen a selection of six different products to try, each of which represent a different method of corrosion control. Here are the subjects for this test…
1. Magnus Cavity Spray
This is a thin wax based product, very similar to Hammerite’s Waxoyl or Bilt Hamber’s Dynax S50. It is primarily intended for protection in closed cavities as the film is really too thin for serious underbody protection but I figured it was worth seeing how well it adhered to the steel and held back the rust. The Magnus Cavity Spray states on the can ‘Penetrates and isolates the first signs of rust’. This will be tested out as the steel samples I have used already have a light surface rust on them.
2. E-Tech Tecknik Rust Preventer
This product is a paint or more specifically, a zinc primer. Obviously primers are meant to be top coated with a paint but for the purposes of seeing just how well this non-porous zinc rich primer protects, I have left it bare. Two coats have been applied. Here’s what it says on the can… ‘90% enriched zinc particles which electro-chemically bond to the metal or steel surface that they are sprayed onto, it creates a permanent non-porous barrier against moisture and oxygen which are the causes of corrosion and rust’.
3. Bilt Hamber Hydrate 80
Now we come to a totally different kind of product. Hydrate 80 is a rust converter but one which also provides a protective coating when dry. It’s applied in two coats at 20 minute intervals and left to dry for 24 hours. Here’s what it says on the bottle, ‘Kills and chemically converts rust leaving a tenacious protective barrier. Can remain unpainted but for long term protection apply finishing paint’. With this in mind, I have prepared a second sample (see below).
4. Magnus Underbody Protection
This product is more like a traditional underseal which provides a thick film with a rubbery consistency. This is the kind or product many people often use on the underside of cars, especially after repairs. It says ‘Magnus Underbody Protection is a rubber/resin based underbody coating. Permanently elastic, it has high water resistance and prevents corrosion caused by moisture and road salt’.
5. Bilt Hamber Dynax UB
This is generally my own preferred method of underbody protection so I’m keen to see how it compares to other methods. This is another wax based product like the Magnus Cavity wax or Bilt Hamber’s own Dynax S50, only UB provides a much heavier film and is almost black in colour. It says on the bottle ‘Firm film polymer enhanced long term anti-corrosion wax designed for the long term protection of steel surfaces exposed to harsh conditions’.
6. Bilt Hamber Hydrate 80 with paint
As mention earlier, Hydrate 80 is designed to be coated for proper long term effectiveness, so I have added a sample to the test which is. This has been prepared in the same was as the bare Hydrate 80 sample but with an additional two coats of satin black acrylic spray paint added on top. The Hydrate 80 surface was not abraded before applying the paint to it.
Now we come to the method of testing. I found a nice piece of bare sheet steel that had just started to get a little surface rust. All the samples are cut from this and just one end covered in the sample coating. As well as general moisture and weather resistance, I hope to also see how well each coating resists rust creeping under it from the unprotected edge. This is the situation you would expect a coating to suffer when damaged by stone chips so it is an important factor.
The six samples have been placed outside in an exposed area outside my workshop where they will get the worst of the weather over the coming winter as well as plenty of sun on dry days. To simulate the kind of conditions you would find on Britain’s wintery roads, I will periodically give them a spray with a salt solution but other than that they will be left alone. This is a long term test so I probably wont have much to report for a few months but I will add an update as soon as anything newsworthy occurs!
UPDATE: You can now check out the first test results HERE
Finally, although not really part of this test as such, I will be preparing one final sample which will be left out with the others.. The reason why I don’t really consider it as part of the test proper, is because this particular coating is not readily available anymore, and not without good reason! It’s somewhat toxic. The final sample is coated with Red Lead paint. This, as the name implies, contains a very high level of lead… anything up to 60% of it! This tin of paint is very old but I am quite keen to test how effective this old coating is. Although lead based paints are no longer on sale to the public in most countries, they are still in use in industry, presumably because they are very tough coatings. The sample was given two coats (brush applied). It will be very interesting to see how well this old paint resists corrosion.