# Anyone made a coffee mug, and used it?



## wormil

I'd love to turn a wood coffee mug (not the travel kind) but I see some issues. Not sure how I feel about using finish inside a mug that will hold hot, acidic liquid. And less sure about not using a finish. It's a conundrum. I have seen wood coffee cups for sale, both commercial and etsy, without liners. Maybe it's a terrible idea? But I really want to try it.


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## Kentuk55

I don't have a clue myself, but, I'll look forward to seeing some answers from everyone. Gr8 question Rick


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## Wildwood

Rick have seen same discussion concerning wood canteens wood cups before. Too finish or not to finish the inside/outside never really resolved.

JMHO, all about wood specie selection and with no finish. Any closed grain wood that will not impart an off flavor or leak liquid while using will work. Trick here is sand to 600 grit, wet surface & let dry. Then use following sanding sequence 600 thru 2,000 grit and burnish with brown grocery bag inside & out. This is how did my hard maple rolling pins.

Most of your penetrating oil finished not durable even after fully cured. Same with any film finish used on normal woodworking projects. Many people will recommend using epoxy or resin as a finishes. Those products are expensive & tricky to apply. Of course majority of people will recommend using plastic or metal liners.

My only experience here comes from wood salt shaker outside finished with poly inside left unfinished and brought into the house to cure many years ago. Long story short wife took off every bit of four coats of epoxy with hot soapy water. Still have that ugly thing some where.

Let us know how you make out.


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## doubleDD

I thought I saw someone here mention ca glue as a liner. Don't quote me but for some reason it rings a bell.


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## thetinman

Wow! What a great question! I talked to a friend of mine who makes barrels and wooden stave buckets. He ardently says to stay away from poly. He says it leaches into the liquids and is not healthy. That's my shortened polite version of the way he described poly finish on anything coming in contact with food or beverage. Actually, it's generally how he feels about poly on anything. He is an old time purist.

For cold drinks, such as his ash milking buckets and barrels, he uses the old time method of beeswax melted and rubbed into the wood.

He does not make barrels or buckets for hot liquids. However, he suggested that the inside could be burned and rubbed to keep it from leaking. I asked about the burnt wood giving a bad taste. He says it will alter the flavor a bit at first but not after a couple of cups. He suggests filling it with warm water and letting it sit to soak up "surface" taste for an hour or so. He's says a cup is not like a burnt barrel used to age Bourbon. The drink does not stay in the cup for years. His biggest concern was the wood splitting given temperature change and the change from wet to dry. But he thinks it can be done if straight grained clear wood is used.

For wood he suggests (in order of his preference) ash, oak or maple.

I don't know if any of this helps. I just found it interesting and this is the info I got.

Terry


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## TheDane

I would go for no finish on the inside. They make whiskey barrels out of oak … during the coopering process, the insides of the barrels are charred.


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## FaTToaD

Rick, great question with perfect timing. I was about to post a similar question but in regards to a wood shot glass. I turned a shot glass out of a magnolia branch the other day and finished it inside and out with four coats of salad bowl finish. Now, I've "tested" it a handful of times over the last couple weeks and I can tell I need to try something different. I can see a bit of seepage on the bottom after the first shot and it certainly smells like whiskey even days after I've cleaned it. I know coffee and a good, stiff bourbon are a bit different but we may end of needed the same thing.

I plan on making a maple, white oak, and cherry shot glasses soon and leaving them unfinished to see how they do.

I've also been thinking about some sort of epoxy or resin. My thought is I can hollow it out, fill the bottom with about 1/8" of epoxy/resin, let it cure, turn a waste block the same shape but smaller to sit on top of the cured epoxy leaving around 1/16" - 1/8" gap around the inside of the shot glass, then fill that will epoxy. Once that cures I can return the inside leaving ~1/16" layer of epoxy.

Not sure how it's going to work but I'm thinking about trying it soon.


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## ChrisK

Found this article with links to the FDA site.

http://www.woodcentral.com/cgi-bin/readarticle.pl?dir=finishing&file=articles_497.shtml


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## donwilwol

maybe some help
http://lumberjocks.com/topics/3043


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## ChrisK

Also found this site:

http://www.all-about-renaissance-faires.com/woodmugs.htm#how

He uses a 2 part epoxy to coat inside and out.


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## FaTToaD

Thanks Chris for the link! I had seen that some time back and forgot about it.

I think my biggest concern is liquid leaking through the wood or the finish and/or wood imparting too much of a taste to the beverage. Though in my case the whiskey may actual mask that quite a bit.


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## Mahdeew

Rick, I posted this in another forum:
Make your wooden coffee cup, get some ground coffee and put it in blender and ground it to powder. put about 1/2 cup of water in the microwave and bring to boil. Slowly pour the powder in the cup and stir. Use the paste to coat your wooden cup and let it dry. Get the excess out and repeat if needed. Now your cup is sealed with coffee. The idea is to never wash the cup which means no milk or cream. Every time you drink a cup of coffee, the coffee will accumulate in the cup and increases the flavor. Use hot bees wax to seal the outside.


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## bondogaposis

Whatever you do, don't use red oak.


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## wormil

Wow, a lot of good information here. I found a guy selling coffee cups who seals them with a 2 part epoxy he claims is food safe for any hot or cold liquid. Google tells me there are food safe epoxies but the only place I found them for sale was ebay, not sure I trust that.

Charring the inside is an interesting idea, I want to try that. Rubbing down with coffee grounds is another interesting idea. Bill's idea of burnishing the inside was the first thing I thought of and he gave me some good ideas. I do use cream and sugar in my coffee, sometimes, so I'm afraid sealing with epoxy might be the only way to keep the cup from going rancid.

Other thoughts, the bottom will need to be side grain which means a glue up. I'm a little concerned that hot coffee might weaken the glue over time. Epoxy might be a better choice there too.

I'm going to scour the local thrift stores and look for a thin stainless cup that maybe I can just glue to the inside. But the chances of finding something like that seem slim. The downside is I don't like drinking from metal cups.

Here we go:
http://www.amazon.com/Trademark-Poker-Stainless-Steel-Holder/dp/B000HK6BHE


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## ChrisK

Look at Master Bond's site.

http://www.masterbond.com/industries/adhesives-sealants-coatings-encapsulation-compounds-food-processing-applications

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=175.300


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## wormil

I saw that Chris but nowhere to buy it, at least in retail quantities.


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## Wildwood

ChrisK!
Information at Wood Centrel & Garrett Lambert article pretty dated same with Michael Dresdner's comments. Anybody remember big to-do over dyes and finishing materials used on children toys from China?

Guess those people not familiar with or read U.S. Green Building Council's, "Green Home Guide."

http://greenhomeguide.com/know-how/article/buyers-guide-to-clear-finishes

Most woodturners not familiar with product MSDS or SDS or read label ingredients or warning & precautions. This article by Jonathan Bizen published in 2006 hits the nail on the head because chemist, regulatory agencies, finishing manufacturers, would not go on the record on which finish is food safe. Yes, some manufacturers claim and label there salad bowl finishes are completely safe for food contact. Well go read the MSDS or SDS, or label ingredients & warnings & precautions. Remember manufacturers do not list all toxic chemicals in the product, and that is perfectly legal.

http://www.finewoodworking.com/how-to/article/food-safe-finishes.aspx

When do salad bowl only finish will use is mineral oil (laxitive) and provide that buyer with a bottle of the stuff. Never use industrail MO or baby oil on a bowl or food contact product.


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## Mahdeew

Wildwood, you mean to tell me that formaldehyde, hormones, GMO products and all those FDA approved stuff are not safe????


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## Tootles

I'm not going to add to the issue of finishes, but I can add something about the issue of hygiene and coffee cups.

A few years ago I worked at a company where we had a weekly safety talk given by one of the employees. When it came to my turn, I thought about talking about unwashed coffee cups - you know, those people whose coffee cup is completely brown inside because they have never washed it since the day they first brought it to the office. Well as I did my research it turned out that there were few if any health / hygiene concerns because it is used for a hot beverage. In essence, you heat sterilise the inside of your mug every time you pour hot liquid into it.

Does that take away one of the concerns if you chose not to apply a finish at all?


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## mojapitt

Great point tootles.


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## Mahdeew

I used to own a restaurant north of Hollywood called Mzzarrino's (still there). We had a Honduran chef whom never washed his coffee cup and it had a 1/8" thick black goo on the inside. One of our dishwashers decided to make some brownie points with him and took his cup and washed it for him. The next day, I almost had to rescue the dishwasher from being on the menu for hamburger meat as the chef was outraged. He had spent 5 years to "cure" that cup by not washing it. It took me almost two hours to convince him that the poor guy meant well by doing what he did. Eventually, the dishwasher was transferred to the garlic peeler position as neither he or us felt he was safe anywhere near the chef. Moral of the story, don't mess with people coffee cups unless you have permission to do so.


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## wormil

I'm not worried about germs. Coffee doesn't get hot enough to kill many germs anyway, unless it's McDonald's coffee  (just a joke, don't want to get off track on that discussion) But bare wood is a pretty effective germ killer. My concern would be dairy products soaking into the wood and eventually turning rancid. I don't believe any oil or wax finish would be effective for hot coffee which I suspect would leach the oils out of the wood; and oil/wax are not very effective moisture barriers anyway (except for paraffin). Maybe I'll just turn a quick cup out of maple and try it, see how it goes with bare wood. Then maybe buy one of those stainless inserts.


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## mporter

Why can't you just use CA glue? I know it's safe because they now stich up heart surgery scars with it. Put a couple of coats on the inside and I think you are good.

I love mrjinx as a poster, but I'm pretty sure never washing your coffe cup is how Ebola started!


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## Nubsnstubs

> I love mrjinx as a poster, but I m pretty sure never washing your coffe cup is how Ebola started!
> 
> - mporter


I'm glad I'd just swallowed my coffee seconds before I read that. It hit a funny spot. I'm still laughing after 3 minutes, waiting to take another sip of coffee from a styro cup.

I have no opinion about what to use for your cup. I do know that red oak for sure will make coffee taste terrible. Don't believe it, make a stir stick, and stir it up. You could put in a cup of sugar, and still not make it taste good.

I would think that since wood always retains some moisture, even with a perfect barrier, the heat from the drink would cause some type of condensation under said barrier, and would eventually cause barrier failure, unless it was the stainless cup aforementioned?.. (I'm surprising myself, because that almost sounds plausible) That's my input, and I'm not saying anymore…........... Jerry (in Tucson)


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## Wildwood

Medical CA glue, not chemically the same as CA for craft & industry use. Depending up type of Medical CA used could very well end up drinking the stuff with first cup of coffee.


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## mporter

What about mineral oil? Or salad bowl finish? I wouldn't have an issue drinking from a cup with CA glue as a sealer. Have you guys ever looked at what in your drinking water? Read that report that they send you once a year. I think what's in your coffee cup should be the last of your concerns.


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## Mahdeew

It is all about flavor and responsibility to one's own health, be it based on perception or "facts". We all can take things to extreme as it relates to our health and die from worrying about the things we consume. Drink water from the tap in Mexico on your vacation and you will have a diarrhea experience you can tell your grand kids for years to come. Go to India and eat a piece of meat that has been hung in open air at 89 degree temperature for two days and you will have a "how I almost died in India" story to share. Our bodies have a tendency to adapt to the the things we consume over time and in time. I remember throwing up for 4 hours after consuming a cherry pie from McDonald's for the first time in my life. My system was just not ready for it and thus it could not handle the chemicals/preservatives.


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## wormil

> Why can t you just use CA glue?
> - mporter


CA doesn't have very good heat resistance, not sure how it would hold up. One way to loosen super glue from your skin is to soak in warm/hot water.


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## stefang

Firstly, I would use birch as it doesn't impart a flavor. I would not use any finish inside. This works fine with a face grain workpiece. However, if you are making these cups from end grain workpieces liquids will leak through the bottom, but there is a way around that problem.

*If you wish to use end grain then it is best to fit a dry long grain bottom into a groove at the bottom of the cup*. If an end grain cup is turned all the way through from wet wood and the long grain bottom is just small enough to fit into the circumference of the cup, then the wet wood will shrink tight around the bottom in a couple or three days and when you pour liquid into it it will swell and be water tight like a barrel. The best groove would be 'v' shaped and about as wide as your bottom is thick and the bottom piece should be shaped to fit into that 'v' groove. I have just used a regular groove too with not shaping on the bottom piece and that worked fine.

Here in Norway many of us use what we call 'tur' cups turned from face grain, usually from birch that we hang on our backpacks when hiking. They work great with coffee.








They work great and clean up fine too.


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## tejon

Context: I make wedding goblets, meant to hold liquid for drinking.

Let me run down how I as a woodworker and a chemist look at finishes for this type of application.

First, let me suggest that if you do a film-forming finish on the inside of the vessel, do not do one on the outside of the vessel. Eventually you will get a small, insignificant pinhole through your interior film finish, liquid will get under the film, and it will have nowhere to go, and will begin bubbling up the film near the pinhole. Unless you allow for the water to slowly work its way out through the unfinished exterior.

Finishes you can theoretically drink directly: mineral oil, walnut oil, raw linseed oil, and pure tung oil
Of these, raw linseed oil and pure tung oil form nice, essentially waterproof films if you give them ample time to dry (and they do take a while!) in several thin coats. Tung oil creates a more lasting film than linseed oil. Mineral oil doesn't dry and although its presence will repel water, it really can't be said to be waterproof. Also, it will tend to leave a slight oil slick on top of your beverage. Walnut oil dries, but has trace amounts of very flavorful compounds that are soluble in ethanol, such as in wine. You may taste a little of it the first few times you use the vessel for booze. No "metallic driers" in these, which means that thicker coats will tend to skin over and fail to dry well.

Shellac: great finish in general and you eat lots more shellac than you realize. But it's alcohol soluble, so pretty much out for drinking vessels. (Feast away on shellac flakes, but do not drink mixed up shellac, because the denature alcohol solvent is toxic!)

Lacquer. Natural lacquers are probably fine, once completely dry. The stuff you buy in a can these days is an acrylic lacquer, and I'd expect it to be fine, but I just don't know enough about the formulations used industrially to say with any authority.

Polyurethane and boiled linseed oil. You may be surprised that I put these two together, but chemically they are similar. They polymerize when exposed to oxygen, forming a high molecular weight plastic that is chemically quite inert. Because they are catalyzed by O2, carboxylated cobalt salts are added that do two things. One, they speed up the curing process by activating the reaction site on the growing polymer. Two, they slow down the curing process temporarily by holding onto polymerization inhibitors that take a little while to evaporate away, giving the applied film time to absorb enough O2 to dry completely before the top of the film reacts and skins over. (Really clever idea there, actually!) The inhibitors leave the film, by definition. The cobalt ions stick around and are embedded in the polymer film. They are not directly soluble in the film, which is hydrophilic, they are merely stuck there because it solidified around them. So you don't expect to see much of them come out. I should say that polyurethane does have low molecular weight petroleum distillates used as a solvent to make it a liquid. Those solvents are chosen in order to be volatile enough that they can evaporate away as the film cures. That's pretty much what you're smelling when you smell polyurethane.

Let me say this about cobalt driers: not only are cobalt ions trapped in the matrix of whatever film they dry, but there's really not much of them in liquid finishes in the first place. As a catalyst, they are added in very small percentages. And the amount of finish that's on the inside of a single vessel is minuscule. There is probably less total cobalt in the entire finish of one of my goblets that present in one of your multivitamins. And cobalt ion is not particularly toxic in the first place, being present in almost identical form in several compounds needed by the body. LD50 is crazy high compared to the amounts encountered in these applications.

Tejon


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## Mahdeew

Mike, I recall birch bark being used to boil water.


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## donwilwol

I was just reading where some turners use Dupli-Color automotive clear. I use Dupli-color for hand planes and it works well. It make sense since its made for high heat applications, so I wouldn't think coffee would affect it, and since its used in automotive, so it should be chemically resistant. I'd personally want to research it a little more before I poured my coffee in it, but its an avenue to look at.


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## wormil

Thanks Stefang. The tur cup looks very similar to what I know as a kuksa and I've always wanted to make one. I've read that beech is another wood that does not impart flavor, although I think birch is cheaper around here.

Don, I will check on the Duplicolor clear.


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## wormil

Found these amusing directions for care of a kuksa:

*KUKSA*

'Kuksa' is a traditional Finnish wooden cup, hand-made from birch burl from Lapland.

Preparation of the Kuksa

Your Kuksa can last a lifetime if you cure it properly from the start, and follow a few simple guidelines:

1. Fill the Kuksa about ¼ full with cognac.
2. Swirl the cognac clockwise so that it wets the entire inside, without spilling over the rim.
3. Drink the cognac.
4. Fill the Kuksa again about ¼ full of cognac.
5. This time, swirl the cognac anti-clockwise as before.
6. Drink the cognac.
7. Next, brew some double strength coffee (not instant)
8. Without washing the Kuksa after the cognac, fill it with the strong coffee.
9. Don't drink the coffee!
10. Leave the coffee in the Kuksa in a safe, warm place for at least 24 hours.
11. Go and have another glass of cognac and relax.
12. 24 hours later (and with a faint hangover from the cognac you drank yesterday) go and find the Kuksa full of cold coffee.
13. Pour the coffee away
14. Rinse the Kuksa with warm water, and dry with kitchen paper.
15. Your Kuksa is now ready for use. The more you use it, the more traditional it becomes.

Care of the Kuksa in use
• Don't use washing up liquid to clean your Kuksa!
• Just rinse with warm water
• Don't drink milk from the Kuksa!
• Assuming it is usually used for coffee, it is good to drink at least one good stiff cognac once every month


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## Mahdeew

Rick, you just have to get you a shot of cream, take a sip of coffee and then a sip of cream at the same time, turn your head rapidly to the left and right before swallowing.


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## wormil

Haha, that would be a solution! Not sure what my wife will think. Actually that's not true, I can guess what she'd think. Maybe a better solution would be go back to making good coffee in my French press or a peculator. I only use cream & sugar in automatic drip coffee. Or just continue drinking from ceramic cups like any sane person.


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## stefang

I wonder if that method works as well with brandy.


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## dhazelton

I would just buy a kiln and learn how to throw pottery.


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## wormil

I turned a maple cup today and finished it with acrylic lacquer, because I had some. After a 2 or 3 coats I'll let it cure completely and when it stops stinking I'll test it first with water then coffee. Will probably turn another and finish it with epoxy.


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## DIYaholic

Eagerly awaiting results of your testing….


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## wormil

Gee, you think these cracks will cause any problems? This piece of maple had wind shake which were hidden until I started cutting. I filled them inside and out with super glue so they should (hopefully) be good to go. This is after 2 coats of lacquer buffed with 0000 steel wool. It feels like glass. Third and final coat is drying now. Tomorrow I'll remove it from the lathe and finish the bottom. My shop reeks of lacquer.


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## Mahdeew

Interesting. Coffee would look good in there.


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## timbertailor

I have had these two Birch cups since 1979. I just do not leave any liquid in them for any length of time and make sure to rinse and dry them after use. Mostly beer, mead, wine, and coffee. Polyurethane will degas and will become inert. Just think of it as clear plastic. Can plastics be caustic? Yes. But safer than most other products we use for food and drink.


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## Mahdeew

Nice looking cups Brad. How did you hollow them out; they don't look perfectly round, but the inside does?


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## timbertailor

> Nice looking cups Brad. How did you hollow them out; they don t look perfectly round, but the inside does?
> 
> - mrjinx007


I did not make them. I bought them. But, they were simply hollowed out with a forstner bit and then sanded with a spindle sander, inside. They are not symmetrical inside or out so sanding really is the key to a good, even cup wall thickness.


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## Mahdeew

Thanks. My initial thought was that the bottom was removed and it was hallowed out with a band saw prior to re-attaching the bottom with glue of some sort.


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## wormil

The birch mugs are so cool. They could have been hollowed green and allowed to dry, that would have caused irregular shapes.


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## timbertailor

> The birch mugs are so cool. They could have been hollowed green and allowed to dry, that would have caused irregular shapes.
> 
> - Rick M.


Thanks Rick. I am an avid Renaissance Fair participant and the uniqueness of these cups garner a lot of attention.
I am impressed with how well they have held up, as well.

I just found a source for some virgin Birch timbers and may be making some of these myself.


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## wormil

My coffee cup is done and sealed with 3 coats of acrylic lacquer. I realize it's smaller than I intended but that's okay, it's the testing that's important. Not sure how long to wait for the lacquer to cure. My instinct is to wait at least a week or until it stops smelling like lacquer, whichever takes longer.


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## SCOTSMAN

I think bare wood should be ok.I also have read that you can use any type of food oil.How long it will last is another question .why not contact some woodturners who do this kind of thing.I personally would just leave it as is,After all I don't want to get that nasty old aids again. Alistair


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## wormil

Been 3 weeks and still off gassing lacquer fumes. You can't smell it unless you turn the cup upside down for awhile so it's probably close to done. I was tempted to put it in a warm oven but was afraid the wood might crack since it was air dried and not kiln dried.


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## wormil

Failure. After only a couple hours of having cold water it swelled and burst. Guess lacquer is not up the job.


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## DIYaholic

Bummer!!!
I was looking forward to a successful outcome.

It ain't spilled milk….
Soooo, go ahead and cry!!! ;^(


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