Painting wood with wood coloured paint - lessons with cetol 771

[markocosic]

We've been having some fun with paint wood....wood colour. Thought this might be useful here.

 

 

This is as far as we got before winter came and stopped play - no cladding to the south gable wall yet, no roof over the deck, and all of our (untreated) C16 busy going black...

 

 

 

Step one pressure wash then bleach it all to heck then pressure wash again.

 

https://www.stafor.lv/gb/stafor-white-wood-whitener-bleach

 

I don't have photos of this process - too busy cursing the wind whilst trying to spray bleaching agent from a ladder - but you can see the "as dried" look here. It's...clean but scruffy and covered in a fine "fur" of all the half dead / half digested wood that got half blasted off with the pressure washer.

 

Whilst at this: shadow gap vertical cladding is a fag to fit if you're at all OCD. Wood isn't a consistent width and you can see +/- 1 mm on a nominal 10 mm gap from a mile off. Doing full 6 metre runs is a complete pain. Moreso off a ladder solo. Doable if you'd somethign to stand the end of the board on but would not reccommend!

 

 

Next step: Scrub...scrub off all the furry bits not with a sander or a wire brush but a metal pan scourer. Paint...with a sponge and cetol 771. This looks like coloured water (incredibly runny) and is supposedly a dispersion of acrylic and alkyd in water. Weird stuff to use; soaks in like a stain then "turns into paint" once it's within the wood itself. (or your clothes, gloves, etc)

 

Ask for "ashen" shade with only 50% of the pigment if you want this "bleached beach wood" tone. Not a clear stain; but a stain that's essentially the same colour as the wood. Top half of this photo is scrubbed wood. Bottom half is the cetol 771-ed wood. This is magic - the proverbial lipstick for pig.

 

 

 

From a distance the effect is more visible:

 

Untreated columns and horizontal beams that we haven't got to yet look distinctly "scruffy" vs the rafters that almost look plastic yet are definitely wood as no two are the same. Weatherproof too. (water beads as if they were varnished)

 

 

 

The underside of the roof is sarking made from the crappier bits of the cladding used on the south wall with a coat of acrylic facade paint in our standard RAL9005. They're a right mix of crappy little bits but being joined on the top of the rafters you'll never see it. Membrane / battens / membrane (it came in a 50 metre roll...don't have any other use for it) / counterbattens / roof then on the top of that.

 

 

I wouldn't (offer to) do the vertical cladding again but this cetol 771 is cracking stuff. I'd never have thought to paint the wood wood colour to protect it rather than just painting it with something clear. Props to she who must be obeyed for that one!

[SteamyTea]

Would it be worth pretreating all the timber with Cetol 771 as a precaution?

[markocosic]

I'd say no.

 

Plan B had been pressure treated columns and woodwork; leave these weather over the summer / winter; then pressure wash / beach the surface / colour. Pressure treated decking boards were also to be purchased for the south wall cladding and the roof sarking and again left to weather (become a little less green / rougher) before finishing. I'd still recommend this approach from a treatment prespective.

 

Plan C was what happened though.

 

Biden's 2021 stimulus kyboshed the pressure treated timber. We mostly received what was ordered in February by March; but trying to order pressure treated timber in March was a no-go because timber futures had shot up (€800/m3 not €250/m3) and this meant virtually nothing in stock locally / everything was on a boat to the USA. Hence untreated timber for the structure. The exposed elements are being treated with this this stuff. Don't splash it about. Do coat over it after it has been applied to stop it washing away. Do explain to the wife that if you're giving her waterproofs and industrial rubber gloves to brush it on carefully that she shouldn't scratch her ears...

 

https://www.bochemit.eu/en/opti-f/p-1/

 

Bees kyboshed using weathered decking boards as sarking and the south 'accent wall' cladding. We don't want any membrane-eating hornets behind the cladding thank you very much. Everything needs to be overlaping / closed jointed but again pretty much all was out of stock locally until the beginning of this year; we ordered when it was available; and it's now either +20% or out of stock again.

 

Next time I'll be allowed Plan A. Either standing-seam rukki-roof...or probably trapezoidal steel with all black landscape oriented PV over the entire thing, clamped directly to the profile, with a small border in either slate or bitumen shingles to size match and make it look like roof integrated PV, and the membrane underneath it for final waterproofing. I'd probably vary this with some solar-thermal collection in the form of 25 mm MDPE between the PV and the trapezoidal steel in hindsight; to cool the PV / building in summer and also rigged up to recharge the ground array for the heat pump.

 

Wouldn't use this 771 in preference to pressure treating though. Would use the bleach if you wanted the colour. (it will kill the green) Time and bleach better yet.