Thread: Timber urn - wood movement challenges

You're correct, of course. The timber will move no matter what finish you use, so you have to make allowances for it. I'd do it like any other box, with the grain running around it, and loose-fitting top and bottom. As it has to be sealed - you don't want ashes coming out - I'd make the slots for the top & bottom deeper, and put some 1/8" plastic tubing or something similar in it as a seal.

Hi,
You could use silicon glass sealant that they stick aquariums together with in the grooves. It allows for movement in the glass or all the corners would part and flood the house.
Regards

There is another approach.
The ashes would normally be supplied in a plastic bag -- if the bag is not normally sealed you could request the crematorium to seal the bag.

Then you will just be making a standard box -- but you wont be cutting the lid off.
finish the box inside and out before gluing.
use a glued in plywood base -- veneered if desired -- and the same for the top.
place the bag with the ashes inside the box before gluing it together.

I would be using dovetail or finger joints, and rebate for the base, which I would put in last, finish the box completely, without the base, maybe even put a recess in the base panel aswell. But before you put them in, do as Duke said and run a bead of silicon around the inside of the box corners, then silicone bead around the base before putting in. The base won't be seen so you can wipe off the silicone squeeze out. And a quick wipe over with finish to finish it off.

But why make the task any more difficult than it needs to be?

Crematoriums regularly package ashes for shipment overseas by air freight.
From memory the packaging is a sealed heavy duty plastic bag within a heavy duty cardboard box. This packaging is good enough for sending the ashes air freight and satisfies most (if not all) quarantine requirements.

I see no reason why the sealed plastic bag can't be inserted into a regular wooden box during the glue up.
It might even be possible to give the crematorium a open top MDF mould to hold and shape the bag while they fill it.