Cypress Pine finish to avoid cracking

[dlannetts]

Recently I built a mitred Timber frame out of cypress Pine, I didn't realise just how much damage a bit of sun could do to cypress, but I do now, worked it out the hard way. Has anyone got any timber finishes they have used on cypress Pine that they know work well to help avoid cracking and drying out of timber? Also I was wondering if I were to use a finish on the mitred ends before gluing the frame together would this prevent the frame from gluing together as well? I ask this as I noticed the worst cracks, came from the mitred ends. Thanks for the help everyone.

[Xanthorrhoeas]

First, I do not claim to be the expert on this - so perhaps someone with more experience of finishing Cypress can also answer you. If you post some photos and dimensions it may help to get an answer. My responses are:

A. "I didn't realise just how much damage a bit of sun could do to cypress, but I do now, worked it out the hard way."

How much sun are you talking about here? a lot of sunlight affects every timber and it will depend on how hot it was, and how dry the timber was as to whether you could have done anything to prevent cracking. For example, if the timber had a high moisture content it would crack as it heats and dries - no stopping it.

B. "Has anyone got any timber finishes they have used on cypress Pine that they know work well to help avoid cracking and drying out of timber?".

I have used a marine oil called Deks Olje with some success. However, be prepared to re-coat at least every year and, depending on exposure, possibly every 6 months. But, re-coating is easy - just apply more oil over the old surface. The timber will still darken. I must say though that, eventually after about 5 years, I got sick of all the work and ended up painting my external Cypress with acrylic house paint.

C. Also I was wondering if I were to use a finish on the mitred ends before gluing the frame together would this prevent the frame from gluing together as well? I ask this as I noticed the worst cracks, came from the mitred ends.

i suspect that sealing the ends before gluing would most likely weaken the glue joins significantly and could only work if the sealer bonded very strongly to the timber and you used an adhesive that bonded strongly to the sealer. Most adhesives such as PVA depend upon being absorbed to some extent by the wood fibres.

Wood dries out much faster from the end grain than the sides. This is because the structure of the wood is an assemblage of a lot of very fine "pipes" (wood vessels and tracheids) with some softer tissue (parenchyma) where the tree stores waste products and chemicals (lignin etc.) Not surprisingly, water comes out of the end of the cut "pipes" faster than the sides of the "pipes" so that is why timber cracks at the ends as it dries.

Hope this helps.

[RoyG]

Recently I built a mitred Timber frame out of cypress Pine, I didn't realise just how much damage a bit of sun could do to cypress, but I do now, worked it out the hard way. Has anyone got any timber finishes they have used on cypress Pine that they know work well to help avoid cracking and drying out of timber? Also I was wondering if I were to use a finish on the mitred ends before gluing the frame together would this prevent the frame from gluing together as well? I ask this as I noticed the worst cracks, came from the mitred ends. Thanks for the help everyone.

Dlannetts,

I think that the first question to ask is "was the cypress dry (well seasoned) before you built something with it. A lot of cypress is sold green or maybe partly seasoned. To me, what you've described suggests that the cypress was still green or only partially seasoned when you built with it, and as a result the cypress cracked and possibly warped as it continued to dry out. The best solution is to start with dry, well seasoned timber, and then it should not crack or warp.

Hope that helps...

Regards,

RoyG