Weathered Wood

[Kristal]

More on this bowsprit, I'm afraid.

Two years without varnishing did not have a very healthy effect on it and, where the varnish has failed, it has understandably weathered to a grey colour, quite dark in places. Having looked at a number of websites on cleaning processes for garden furniture and decks (the garden type), and posted a request for advice on the US Wooden Boat forum, it seems that oxalic acid is the way forward, perhaps combined with a pressure wash, before sanding. It was stated by one poster on the WB forum, though, that fir or spruce, the most likely candidate for the composition of the spar, do not react as well as, for instance, teak.

This raises two questions - has anyone had any particular success in dealing with weathered timber using this or any other method, and is it perhaps worth attacking the visible teak on the yacht herself with a bit of oxalic acid before whacking on the Coelan. I seem to recall someone, possibly Mirelle, advising against using anything on the teak before application in a previous discussion, but I cannot be sure.

/<

 

[tillergirl]

I did my spinnaker pole this last winter after some disgraceful neglect for which I have little excuse. It took quite a few applications of oxalic acid to get the colour back although some deep black spots have not been eliminated. I think I would agree that it doesn't react as well to the bleaching effect as say iroko or teak. You are now going to ask what the pole is made of and I think the answer is sitka spruce. In one or two spots a not unpleasant faint reddish tone appeared but this did not discolour the final varnished finish.

As to other treatments, the 'Woodworker's Pocket Book' says "for a more drastic bleach to produce the effect known as 'bleached mahogany' etc, a powerful proprietary bleach is used on the bare wood. This will take the redness out of Honduras mahogony, leaving it almost white. It should be finished afterwards with white polich. Cuban mahogany cannot be bleached successfully.

A mild bleach is a mixture of 1 part 0.880 ammonia and 5 parts water. When dry, follow with 100 vol. hydrogen peroxide diluted with 2 parts water."

No experience of using this I'm afraid.

The advice on the use of oxalic acid is "Dissolve 1oz of oxalic acid cystals in half pint of hot water. Apply to work with rag. Several applications may be needed. Wipe over with borax, about 1oz to half gallon of water. Wash with clear water and dry. Oxalic acid is a poison and should be kept from the fingers. Remove all traces from the work, otherwise it may attack any subsequent finish."

 

[SteamShipW]

International paints used to produce a yellow stain for spruce which also helped restore some of the original golden glow. maybe a combination of bleaching the timber, then staining the bare wood (cloth not brush) would do the trick.