I'm very proud of the teak decks on my boat, but I have to admit that sometimes they could do with some TLC. My son and I have an occasional discussion about the fact that in his view some of the other teak fittings would at least benefit from some teak oil. Maybe I'm influenced by my previous experience with a motor cruiser we owned that came with varnished teak parts, and which seemed forever in need of refurbishment. Anyway I like the silver grey look and I'm told that the natural oils in teak do the protection job for me. But is this true?
Take a good look at your deck
What condition is it really in? How sound is the caulking? Has your vigorous scrubbing been removing the surface? Do you know what cleaning products you have used in the past?
Natural weathering
Teak just like other materials will be subject to Oxidation a natural process when exposed to weather which causes a chemical and physical change. The longer the exposure and the harder the conditions, the more change will take place.
The change in colour to a grey or light silver colour is partly caused by degraded cellulose fibres and micro-organisms. As time passes and the weather does its work, then fibres will be lost from the surface.
Changes after cleaning
A grey appearance can appear after 2-3 weeks if you have used some chemical cleaners.
Black or dark brown contamination is usually due to a weathering condition causing mildew. Again some oils and solvents create a temporary cosmetic improvement but actually promote the tendency towards mildew.
Darker spots, often show that an earlier use of resins or varnish have penetrated the grain. These are often very difficult to remove. Simply sanding down will not do the job. A chemical remover will have to be used. As you rinse between applications of the removing product, check the colour of the water. If the contents are white then the job has been successful, if the water is light or dark brown in colour then more chemical cleaning is necessary.
If you can, decide what products have been used in the past
Oils which have been mixed with resins, polyresins and urethane are all related to the varnish family. You will need alkaline and acid to strip clean the surface of residual coatings.
If you have used Silicone products, they need specialised solvents to clean effectively. If you plan to eventually use a non-silicone oil, all traces of the original product must be removed first. Mixing products from different suppliers can create serious incompatatibilty problems.
Penetration is the key to success. You should try to avoid oils which contain varnishes, resins, polycarbons, silicones or urethanes.
Cleaning techniques
You can clean teak without knowing what has been used on it before. But it is better if you do know, so that the appropriate removal materials can treat oxidation, mildew or residual traces of varnish. Two-part cleaners have been known to cause problems in long term use. The best method is to use a balanced pH wetting agent detergent. These are able to separate the oils and other elements that have oxidized the teak. Removal is then made easier, often a simple matter of washing off the resultant detritus. Cleaning can then be done by a gentle product that does not contain caustics or acids.
Protection
If you want to avoid mildew, caused by organic oils. You should consider water-based acrylic teak protectors which last longer, are easy to apply and are environmentally friendly. You should use a brush or pad to apply a thin coat to the teak surface. The surface should be clean but it can be applied to either a dry or slightly damp surface. A period should be allowed for the first coat to dry. Two thin coats are better than a single heavier application.
