Don't seal it.

I was speaking to an aircraft restorer many decades ago who told me the wood needs to 'breathe'. That is, its humidity needs to rise and fall along with the humidity of its surroundings, he had a humidity probe which he poked into woodwork of airframes.

I appreciate an A7 ain't gonna fall out of the sky through wood rot, but a breathable coating would seem to be best for long term preservation.

Hi Derek.

I have always used clear, solvent-based Cuprinol or Ronseal with very good results. You will probably have to go to a proper builders' merchant to find it, as most DIY stores and Screwfix now only stock the water-based stuff, in which I have very little confidence, particularly when used on a fairy dense hardwood like ash.

****! What am I doing? Giving away trade secrets for free!

Location: Herefordshire, with an "E" not a "T".

Well done Martin, devious bugger that I am I opened the question to the collective hoping to catch you.
No really , thanks for the advice.
Ps don't forget that you have the invitation on my Rosengart F.B page

Location: Oakley hants

You're welcome, Derek.

I did accept the Rosengart Group invitation a couple of months ago, but for some reason it didn't go through. Anyway, I'm now your newest member! Some very impressive work there - it's looking great.

Location: Herefordshire, with an "E" not a "T".

Clear Cuprinol gets my vote as well, thats the stuff we put on our ash frames before panelling them.

Location: New Forest

Martin,
I'm going to take that as a compliment from the Grand Master.
Thanks

Location: Oakley hants

Same here. Cuprinol 5 star. Solvent based.

Is it just me, or is ash very prone to rot if it is left damp?

The living van I tow behind my traction engine had worm and some rot. The rot was removed, its not always neccassary to remove the worm (bits of 4x3 and 4x4), so it got treated.

I must have used 10 gallon of the stuff. No sign of more worms in 3 years.

It recommends 3 coats. I found a garden pressure sprayer the easiest way to apply, untill the solvent rots the rubber seals!.

Blackfriar also do a similar product, I think I exhausted my suppliers source of Solvent Cuprinol and used a gallon of that. It smelt ad felt the same, but then it would its mostly white spirit.

The body framework for the Gordon England Cup has also been liberally soused in it.

How much should I need to do my own Cup body do you think Hedd?

1/2 a gallon. Buy a full gallon and youll have spare.

Thank you Hedd.

Derek, I have no experience with wood on cars, but rebuild wood and canvas canoes. They traditionally use white ash for stems, gunnels, thwarts and seats. A good oil based varnish like Epifanes, is commonly used for brightwork. Thin up to 30% for the first couple of coats so that it soaks in well. However, varnish will require sanding between coats(unless "hot" coating) and while it seals the wood well, any fastening will let water in. The easier method is to use boiled linseed oil or tung oil. I prefer the former. Again, thin the first coats, with either thinner, or turps. A good build up will last a long time and it doesn't need to be sanded between coats. Ash is a very dense wood and amazingly bendable, but it is not very rot resistant. I would not recommend using synthetics like epoxies. They don't breathe whereas the oil based varnishes and oils do. Varnishes do look nice and can last a long time if built up with thin coats. But they can peel or chip, the latter if the wood gets wet. They key to preventing water from getting in, is to seal all parts(like the back sides with an oil before varnishing the outside. Epifanes products I use are Rapid Clear, which gives a good fast build, and Gloss Varnish for tropical woods as it has a lot of oil in it. If this is for wood that doesn't see daylight, I would use the oil method and coat liberally with thinned oil, especially around joints, corners and any fixings. On canoes, the latter is where the water can get in. If the old starts to turn black, it won't hurt the wood, but you know you have water getting in.

Hope that is of some help.

Location: Sunny Seattle