Drying timber slabs - how important is vertical weight?

[RSD]

When drying timber slabs does the vertical weight imposed when storing them as a stack with stickers in between play an important part in keeping them flat or will one slab stored on stickers with nothing above sray just as flat?

[BobL]

Depends on a bunch of factors like drying area setup, thickness of slabs, type of tree and presence of stresses in wood.

In general some weight/force is better than no weight and the more the better
This is demonstrated by the way that slabs at the bottom of a pack are usually flatter than those near the top.

I've seen some slab millers put 100 mm thick concrete slabs on top of their packs - forklift required.

For a while I was steel banding my slab packs but then you have to remember as the timber dries it shrinks so the bands become loose allow the slabs to twist so they need constant tightening with wedges or similar.

I've also used ratchet straps but unless they're super heavy duty straps they're not very effective.

[rustynail]

A through and through cut log produces both quarter sawn and back sawn slabs. If you are short on dunnage to weight the packs it is a good idea to place the back sawn material on the bottom and the quarter sawn on the top. This can be either within the one pack or a pack of back sawn weighted with a pack of quarter cut. The quarter cut material will hold it's shape much better than backsawn.

[stihlsawer]

Depends on a bunch of factors like drying area setup, thickness of slabs, type of tree and presence of stresses in wood.

In general some weight/force is better than no weight and the more the better
This is demonstrated by the way that slabs at the bottom of a pack are usually flatter than those near the top.

I've seen some slab millers put 100 mm thick concrete slabs on top of their packs - forklift required.

For a while I was steel banding my slab packs but then you have to remember as the timber dries it shrinks so the bands become loose allow the slabs to twist so they need constant tightening with wedges or similar.

I've also used ratchet straps but unless they're super heavy duty straps they're not very effective.


I am contemplating on using 3" ratchet straps myself and I have heard of people using them. Cheers.

Trever

[rustynail]

I am contemplating on using 3" ratchet straps myself and I have heard of people using them. Cheers.

Trever
Straps do have one problem... they are not self tightening. Once the pack starts shrinking, during the drying process, the straps are constantly loosening, which means they must be constantly tightened. Top weight is constant and requires no maintenance. My weights of choice are the 1000ltr IBC tanks filled with water. Easy to move when empty and rock solid when full. The 1.2 x 1.0 fits perfectly on a metre wide pack and the 1.2m length works well with 300,400 or 600mm stickering.

[Mr Fiddleback]

Keeping crown cut stuff at the bottom of the stack and quarter/riftsawn stuff at the top will work wonders in controlling any degrade during the seasoning process
Interestingly I have seasoned material vertical standing in the past without major issues
There is a definite art in the process of seasoning green lumber
Make sure the shed temperate doesn't fluctuate too much and that the timber is correctly milled from the get go!
Mr Fiddleback :)

[Bushmiller]

Weight on the top is a must. This was old tyres on rims and not really enough:

488803

This is a little better with the addition of concrete blocks;

488804

The same stack built a little higher.

488805

Ideally you place as much weight on the stack as you can (within reason), but in practical terms for a hobbyist we will fall a little short of the ideal. Much depends on what sort of weight you have conveniently available and your ability to lift that weight into place.

Nice evenly spaced timber of the same dimension is preferable but often a luxury that is unobtainable for a backyard scenario.

Regards
Paul