Thursday, 1 October 2015

Oxalic Acid

Now there's a dreary sounding blog title, and it will indeed be backed up by a fairly dreary blog. So if you would prefer a blog about golden autumn leaves falling patiently and unnoticed in the evening and touching before they collapse into the blackened canal, then you would be better off googling Keats or Blake or someone more interesting.

For those of you left, we will begin at the beginning.

Now NB Princess Lucy is around 15 years old and some of the inner ash window trims have suffered a little with water damage. This is only through condensation, but over time those nasty black marks have grown and they don't look pretty.

First, I tried sanding them out, but the marks were too deep. Plan B was to renew all the trim. I made one window trim (the smallest) which took a good day and made plans to do the rest. At one a week it would be done well before Christmas.

Before you could say Screwfix a new plan evolved. Enter Jim Cook (of Chertsey fame - and many other boats). He suggested Oxalic Acid. What?

Well, according to You Tube, Canal World, and other popular sites that have the answer to everything (I didn't check mumsnet), oxalic acid will indeed remove water marks from wood! So armed with a kilogram of the (fairly nasty) stuff, I set about the second window.

The results are shown below. It is not going to pass as brand new, but I think it will do, and hopefully as I progress through the boat there will be the usual learning curve and those windows more on display (saloon and galley), will look better still.

Hopefully which picture is before, and which is after, is obvious!

The new (clear) varnish has left the wood a little lighter than before, but a weakish mixture of some coloured varnish I use for making pine look like ash should help here.  (It is a 50/50 mix of beech and medium oak varnishes).

Tomorrow, we will try the trims on the boat and First-Mate will raise her hand into the air, and the thumb will either go up - for Jim's Acid Method, hereafter called "JAM", or thumb down - for a winter chained in the garage, planing, and choking on sawdust.



2 comments:

Marilyn McDonald said...

An impressive solution - where do you buy oxalic acid? I could do with some here on Waka Huia.
Cheers, Marilyn

Jemma said...

Hi Marilyn, The product was from a company called ABC Pure, but I bought it through their ebay shop (£6.95/Kg delivered). It came with no instructions, but the mixing ratio (having done a lot of googling) seems to be about 10gm of acid crystals per 100ml of warm water. The stuff is fairly nasty, so you need face mask and all that sort of stuff. I noticed it most when sanding down - when the acid crystals formed an evil dust.