Stinky boxes

[David Gilbert]

I’ve been making some swivel top saltboxes. They are easy and fun to make but I’ve come up with a problem and I don’t have a good solution. I finish the boxes with my combo finish of tung oil, high gloss polyurethane and odorless mineral spirits (1:1:1 ratio by weight). When the boxes are stored in a closed position, the insides start to smell. It’s not a terrible smell for a woodworker but others have objected since these are intended to hold salt for seasoning our food. Some of the bowls were finished inside and out while I took pains with others to keep the finish only on the outside. Both of types of boxes have the smell. I know that this finish is food safe once the solvents have evaporated so it’s not the safety but just the odor that I am worried about.

I am willing to consider other finishing materials.

Are there treatments that will mitigate the odor?

Any suggestions?

Cheers,
David

[Chris A Lawrence]

Tung oil takes a long time to cure. If the wood you are using is an open grain wood you could be getting wicking through the wood if you use a lot of finish on the outside. I did that once by accident on a salt box. I kept putting my mix on until i noticed the end grain spots on the inside were getting wet. If you don't put finish on the inside you can use anything on the outside as its not touching the salt.

[John K Jordan]

Are there treatments that will mitigate the odor?


What I would try at this point is open the box and put it in a warm, ventilated place until the finish fully cures. I think the smell should eventually go away.

For future boxes you might try a sealing coat of shellac on the outside and let dry before applying your preferred finish. This should keep the poly and oil from soaking into the wood.

I sometimes finish things like that with beeswax but it's not glossy or very durable.
When I finish with "danish" oil the finish has an odor but after a few weeks or a month or so I can't smell it.

[Thomas Canfield]

I use a drying box (actually a large cardboard box with vent holes with a heat lamp inside) to speed up the drying of my Danish oil blend similar to yours except using BLO vs tung oil and 1.25 for gloss varnish. The little extra heat both raises the temperature and lowers the humidity to speed drying and usually 2 or 3 days for wiped off coat produces dried surface with no odor.

[Richard Coers]

Did you put finish on the inside, on the seam, or did it just leak through the wood grain? A couple of coats of shellac on the inside may mask the odor, maybe not. One of my early projects for our 39 year old son was a desk. I made the mistake of using poly on the inside of the pencil drawer. It stunk for the decades, probably still does. The best finish for salt boxes is nothing.

[Reed Gray]

The problem with the penetration oils that are solvent based is that they take a day or so to be dry to the touch, but a month or so for all off gassing to pretty much stop. I only use walnut oil or Bull's Eye spray lacquer for the inside finish. No off gassing from them at all.

robo hippy

[Prashun Patel]

The problem isn't the poly, it's the tung oil. Either you love it or hate it.

I would finish the interiors with shellac. This is foodsafe, does not need a long time to cure, and will not impart a taste to the salt stored inside - which will otherwise absorb the flavor of the tung oil.

Or sand the inside to a high sheen, and don't finish it at all.

YMMV.

[Karl Loeblein]

Rays from the Sun can help eliminate odors and harden finishes (unless the wood's color is adversely affected by UV rays and/or oxidization). Similar to Thomas's drying box suggestion, but using free energy.

[Tom Bender]

Odorless mineral spirits? actually, not so much

[Terry Wawro]

Shellac is the best choice to seal in/out odors. I think your only choice at this point is to let them air out for a least two to three weeks. Then apply about three coats of shellac on the inside.

[allen thunem]

just curious why finish the inside at all? if they are salt boxes wont the salt, being so corrosive, eat the finish any how???