Appropriate finishes for repeated water exposure
BillieRuben
| Posted in Finishing on
Hi! I want to make a little dish-drying rack, that fits into the windows above my sink. Given it will regularly be wet, what would be a good finish for the wood, to reduce the risk of mould? Bearing in mind it still needs to be food safe…
I’m thinking maybe a drying oil? Like polymerized walnut or linseed?
I’ll probably make it out of a scrap of hardwood. I’m in Australia so I have a bunch of grey and red gum that might work.. I’m just not sure if it’s been treated… :\ Are there ways to tell? It would be CCA if it was.
I was thinking of trying to design it such that water will be less likely to enter via the grain, Maybe even adding bits of brass to areas?
I dunno! All thoughts welcome. ☺️
Replies
I would use no treatment at all.
If anything an oil.
The alternative is to encase it in plastic with epoxy.
These items commonly get a lot of wear so it's unlikely that it will stay looking flash for long, and an oil like BLO or mineral oil is at least easy to repeat for a refresh.
BLO isn't foodsafe, it has heavy metals added to decrease drying time. And mineral oil doesn't really dry. But it might be ok if I apply lots... I'm mostly worried about mildew, not really looks so much.
Not knowing exactly how this will be used, I have used exterior grade marine poly on my mahogany bench. It holds up well for 3-4 years before I have to refinish. The wood is fine. This sits outside so some of the degradation is due to UV exposure. With regard to food safe, I would think you would have to eat some poly to have a problem. I'm sure others will have an opinion.
Oooh I'll look into that, thank you! I didn't think about the boat world. You're a gem!
You might want to try terrified wood some times called tempered wood. Once the heat treatment is complete the cell structure is changed and closed. The result is wood that is hydrophobic or water repellent. The oak I have that is terrified is brown throughout and look great. The wood breaks like tempered of safety glass rather than splinters.
Dang! I'd never even heard of this! I'm off to the Google machine, thank you!
Consider choosing a wood that you would use outdoors instead of random scraps. If you're putting in the time to build it you might as well give it the best odds for a long life.
I'm with Rob_SS... no finish or just an oil, or maybe a mineral oil & wax mix if you're on the food-safe bandwagon.
Red/grey ironbark is often used outside untreated, as sleepers, even here in Aus where we have termites and tropical conditions.
They're an extremely hard hardwood, for reference hard maple has a Janka hardness of 6400N and white oak 6000N. Grey ironbark is 16300N. More than 2.5x as hard.
It's like picking up a brick. And they're naturally rot resistant too (thanks to being a eucalypt, if I recall).
Hence why I want to use these pieces.
Also because yay, recycling! There's enough stuff in the world, methinks. And it's nice to reuse. ☺️
Plus the woods are beautiful, these were scraps of old sleepers that I've planned back...
Nice! Sounds perfect.
Just wanted to chime in with this:
https://www.finewoodworking.com/project-guides/finishing/food-safe-finish-considerations
Long story short, after it's cured there is nothing to worry about with dang near any finish. Just don't eat the finish!
I would vote for Tried and True or another linseed oil-based finish (without dryers) that's easy to reapply. I bet a film finish will flake off eventually.
Thank you! That's the way I was leaning too, I think a polymerized drying oil like linseed or walnut. Might look at what exists for chopping boards 🤔 thank you for the article! I didn't find that in my searching. I'll give it a good read ☺️☺️
Autocorrect is not always helpful. You will get more useful search results looking for “torrefied” wood.
Thermal modification is a similar but not identical process (according to my research, anyway) that might also be of interest here.
Oooh thank you!! ☺️☺️
Epifhanes marine varnish. ANY finish is food safe once it is cured. another option is to use what bars use for bar tops. Rockhard Table top varnish. Behlen used to carry it but their product has been bought out by Mohawk Finishing. Rockhard varnish will look plasticky but you can rub down the sheen and not lose its ability to protect against water.
Oooh great thoughts thank you!