“For some time I have been storing my boat in my friend’s metal factory to keep it safer. But I think it was a mistake. When I was doing a general cleaning a few days ago, I saw some rust stains sprayed on some parts of the stern area and the cockpit. My question is the following: How can I clean this rust? On a small part I used auto polishing and cream cif. They both clean it, but neither of them provide a deep cleaning. I do not prefer the auto polishing, because it causes very thin scratches. The cream cif causes no harm. I need a cleaning agent that will get rid of these kinds of stains and spots and will not harm the boat.”

Flying iron particles are found in places where iron based metals (steel, pig iron, chrome-nickel / stainless steel) are treated, especially cut and ground, getting on the surfaces nearby. Especially when they are hot, they melt surfaces such as gelcoat and get buried in them. Later, upon contact with water, they start turning into rust (iron oxide) and form spots like those seen below.

The damage formed is cosmetic. When the damage is heavy it may decrease the value of a boat.

1 – A large iron dust on broadside and the gelcoat crater and the rust circle it formed.

2 – It is more difficult to get rid of the rust particles on a pyramid patterned non-slippery deck.

These iron dust spray traces can be removed. However, as our valued reader has pointed out above, one should avoid causing different kinds of damages (such as scratches). Besides, removing is a process that requires care and is tedious. Should a boat owner be unable to accomplish this removing process on his/her own, then there might be additional problems. For when the job is given to an outside contractor, initially he/she may underrate the scope of the job.

As for the pyramid or sandy designed non-slippery surfaces, since particles may penetrate more easily their removal may be much more tedious.

Since we come across iron dust damage often, at some point, we made some experiments and examined the rust removal capability of various products.

The four products we examined were 3M’s Fast Cut Compound (Product No 09374, abrasive polish), Star Brite’s Rust Stain Remover and also the oxalic and the phosphoric acids we had obtained from the cleaning and chemical depots.

Our method consists of applying the abrasive polishing with a soft and clean cloth, rubbing the other products with a small brush into the dust particles and wiping them with a clean cloth. It may sometimes be necessary to repeat this application a few times.

Of these only the Fast Cut Compound has an abrasive quality and it requires, following the first phase, a progressive thin abrasion and polishing. If the procedure is carried out with care and in correct order the surface shininess will be close to a gelcoat just out of molding.

Using chemical reaction, the other three products transform the iron oxides into compounds that can be rinsed by water. It will be necessary to rinse the area after every kind of application. However, since phosphoric acid is much stronger than oxalic acid, the rinsing process is much more important in this case.

As we see in the photographs for comparison, all the applications tried by us gave similar results.

Our recommendation is that with the exception of very heavy duty problems (In a heavy damage iron dusts will “penetrate to the nail”, see below Figure 1), one should stay away from abrasive products as far away as possible, and stay away from auto polishing under every condition. Although the abrasive products clean the surface, they will, instead of transforming the iron oxide particles, spread and smear them. Therefore, after contact with the sea, these oxides will again continue bothering us, this time, in the form of a much more spread film. In other words, the correct approach in heavy damages is to have a chemical cleaning after the application of abrasives, and, following a thorough washing, to polish the area using a correct product.

In lighter damages the chemical treatment will be sufficient. In small surfaces, we recommend using a rust stain remover, which is easy to keep and handle in the boats. In widespread damages such as the one described by our reader, one should first try some oxalic acid, and if this does not work, some phosphoric acid.

In the meantime, one should certainly prefer preventing damage rather than removal. Unfortunately, the source of damage, as stated by our valued reader, can not be determined clearly in every case. Especially in the economic anchorage and slip possibilities, businesses tend to place boats separately according to their types. Apart from this, even though some businesses limit “scraping, welding, cutting, grinding, sanding operations” needed in the metal boats in their regulations, they do not check these operations sufficiently. Moreover, the personnel and the contractors who work on metal boats do not show the necessary care. Therefore, when a proper anchorage/slip place is being chosen the boat owners should show more awareness and consider the sensitivities shown to the topics we have been trying to explain here.

Moreover, as I stated in the beginning, the metal dust generated during the processing of stainless steel / chromium-nickel accessories such as stanchions and connecting frames will cause dust spray. Therefore, preventive measures should be taken during cutting, welding and grinding done on the boat of the chromium-nickel components in order not to cause any damage both to the boats around and the boat where this process is taking place. These measures will usually consist of camouflaging the area where the process is taking place with products for catching such particles. In this context, I can say that salvage carpets do a good job.

Our valued reader has established that the problem originated from leaving his boat at a place where iron work was done. However, generally, it should not be forgotten that iron dust spray damages are external and usually due to the factors outside the control of the boat owners. Therefore, I would find it useful that in these kinds of damages one discusses the matter with the damage experts of one’s insurance.

Product	Before the Process		After the Process
3M Fast Cut Compound 09374
Star Brite Rust Stain Remover
Oxalic Acid
Phosphoric Acid
Pyramid Patterned non-slippery Surfaces
Before the Process
After being treated with Phosphoric Acid

Cushion Basin, Before (left) and After (right) Treatment With Phosphoric Acid

All the photographs are from the archive of marineSOLUTIONS