# Waterproof yet food safe finishes?



## WeebyWoodWorker (Jun 11, 2017)

So my cousin got engaged and as the resident wood worker I'm always expected to make a ton of gifts for everyone on every single ccasion. I'm normally happy to do this (although I would rather be asked not expected) but on this occasion I now have to figure out some things. Now my cousin wanted a cutting board as her wedding gift. Easy, simple and quick no problem as I make those all the time. I just finish it with some mineral oil and beeswax mix. Her fiance though wanted a coffee mug. I've made plenty of mugs before but I never use them so a plain oil finch is fine, problem is that this guy drinks coffee nonstop so it isn't a decorative piece. I don't really think polyurethane is food safe and the only other waterproof finish I use is super glue which I also don't think is food safe ( It would be great if it was though! That stuff's an awesome finish in my opinion!) I've heard shellac is food safe but I'm not quite sure about it as it mainly comes in flake form which is sorta weird. Any suggestions?


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## Terry Q (Jul 28, 2016)

This has come up in the past, and I'm not sure any of the wood finishes will hold up to hard, long time coffee use. How about making a wood cover for a stainless insert? Lots of them come up when searching, first one on my search was http://www.rockler.com/travel-mug-turning-kit


In woodworking there is always more then one way to accomplish something.


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## Steve Neul (Sep 2, 2011)

Any finish made after 1978 is food safe. I'm just not sure how polyurethane would hold up to the heat of coffee. Shellac would even be more vulnerable to heat. I believe I would be inclined to use a marine grade spar varnish.


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## Quickstep (Apr 10, 2012)

I'd use this:

https://www.woodcraft.com/products/16oz-stainless-steel-travel-mug-turning-kit-with-screw-top-lid?gclid=EAIaIQobChMI79q11a6p1QIVxiOBCh1YHAWyEAQYAiABEgKX2PD_BwE


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## WeebyWoodWorker (Jun 11, 2017)

I could use a stainless steel insert, I have one already but I had wanted to go with a "Classic" mug look, I just enjoy making those more. I'll probably end up making both types and just tell not to drink coffee from the wooden one.


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## WeebyWoodWorker (Jun 11, 2017)

Steve Neul said:


> Any finish made after 1978 is food safe. I'm just not sure how polyurethane would hold up to the heat of coffee. Shellac would even be more vulnerable to heat. I believe I would be inclined to use a marine grade spar varnish.




You seem to suggest "Marine Grade Spar Varnish" quite a lot. So I'm assuming that it's not only what you mainly use but it also a very good finish in general.


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## Steve Neul (Sep 2, 2011)

WeebyWoodWorker said:


> You seem to suggest "Marine Grade Spar Varnish" quite a lot. So I'm assuming that it's not only what you mainly use but it also a very good finish in general.


Actually it's been several years since I've used a spar varnish. It's been that long since I finished anything with a clear finish that didn't go someplace climate controlled. A spar varnish is made elastic enough to expand and contract with the temperature extremes of being outdoors in the sun. Wood when exposed to heat is going to expand so the finish used in that application needs to expand with it. Harder finishes such as polyurethane would crack if the wood were to expand that much. This is the reason I recommended a spar for a coffee cup.


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## WeebyWoodWorker (Jun 11, 2017)

Interesting. Finishes are somewhat of a mystery to me, I should really experiment more with assorted finishes anyway so this should be an good starting point I guess. I do need to finish some outdoor material anyway!

I do wonder about CA glue as a finish though. You have any experience with it? I use it all the time for my small turnings and projects but I don't know if it would be okay as a "Food Safe" finish. Not for a coffee mug of course, but I make a ton of chopsticks (yeah this again) and the main complaint I get with them is that the wood soaks up water and eventually degrades the overall look and function of it (They tend to warp an awful lot when people decide to leave them in the sink for long periods of time. Who could have guessed?) CA glue leaves a nice waterproof (as far as I'm aware) clear coat that would solve that problem. But I'm not sure if it would be okay to eat off of though...


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