Cracking wood

[koala107]

HI, Im very excited to have found this forum!
I have a question that has long been bugging me - is there a way to stop green wood from cracking as it is drying?
I have tried painting the ends of branches with oil paint whilst leaving the bark on, shellac, rubbing in linseed oil, etc but usually I still end up with cracked wood.
Also, which is better to use, raw or ready-to-use linseed oil? What is the difference?(apart from that the latter has been processed)?

Many thanks, I look forward to spending time here!

[Ianab]

Sorry - no easy way. :(

The problem you are dealing with is that the wood shrinks different amounts in different dimensions as it dries. For example it may shrink 4% radially (measured from the bark to the core) but move 8% tangentially (measured around the log). Now it's very difficult to make an object shrink 4% in dia but 8% in circumferance. That difference is usually made up by a split.

By coating the ends you slow down drying at the ends, and reduce the chances of cracking there (the ends will otherwise dry faster then the rest of the board and split more). It doesn't help the overall shrinkage once the log does dry. Same for any coating really - they may slow the drying and protect the surface but the movement is in the basic structure of the log.

You may get better results from wood that shrinks less (softwoods like cedar and cypress or walnut) and in species that have interlocking grain (are naturally hard to split).

Other strategies are to create an artifical split ( by running a saw down the log ) that can then be positioned in a less obvious place, rather than letting it split at random. Plan B is to let it split and call it character - then it's a feature not a flaw. :D

Cheers

Ian

[echnidna]

As well as coating the ends its good practise to remove the bark

[koala107]

Thanks for your replies, fellows.

At first I was removing the bark, but then thought it might slow the drying, and hence avoid the cracking, if left on and removed later....:rolleyes: haha...

Which species of wood have interlocking grain?
Ive been using mainly thickish fruit-tree branches and eucalyptus (various types) .

Thanks,
Cheers

[Toymaker Len]

Hi Koala, I've found that fruit tree wood splits like hell and there is nothing to be done about it except cut the rounds straight down the middle. The other question about the linseed oil is that raw linseed doesn't dry very well and treated or boiled linseed will dry. Mind you I don't use linseed at all these days as long term it lends a sick yellowish tinge to everything besides having a tendency toward the sticky unless you very carefully rub it off anything it is applied too.

[Gos, Power Tool]

There is a sealing product from Mobil called Mobilcer if you paint ends and 300mm up all sides vastly reduces cracking especially in slabs. I use for my Lucas Mill after cutting. hope this helps!:)