Comment by robhlam | Hacker News Reader

Comment by robhlam | Hacker News Reader

I treat the spoons and ladles I carve with food grade organic flax/linseed oil and roast in a fan oven at 180 deg C, giving a robust coating that is also very safe. A few coats are required to fill all the pores in the wood for a beautiful satin finish but all the coats can be completed in a couple of hours total. Colours start at a something slightly darker than the natural oil colour and darken to the colour of chocolate depending on how long they’re in the oven for. The smell is of hot cooking oil unless you go for full chocolate brown in which case it starts to smell of burnt oil and a bit smoky. Fully dry your item first and heat it up slowly in the oven to 180 deg C before applying the first coat so that all areas cure and colour equally. Saturate the wood initially then wipe off all excess with a paper towel which you can then use to add the subsequent coats. Check on the spoon and remove any drips that appear during roasting before they harden. Silicone oven mitts are great for handling the spoons while hot.

Author here, I also bought a dehydrator to keep my finished spoons at 70C (158F) for 10 hours to speed up the curing of the tung oil. It really works wonders!

I prefer to keep the original color of the wood I sell, so lower temperatures are better for me, but I like the look of toasted wood as well.

My problem with just oil is that the finish is very matte, hence the wax and resin complication I'm going through in the article. But matte is also a look that people look for so there's no problem in that, it's just my personal preference and style that's different.

Do those oils polymerize at that temperature and are those polymers food safe? Also how stable are they since spatulas routinely come into contact with high temperatures?

I honestly do not know because while I have read that specifically boiled linseed oil does cure to be safe it was not clear to me whether it was safe for skin contact or fully food safe and food safe isn’t the same thing as safe for e.g. stirring pasta as it boils or stirring food that is frying in oil.

Boiled linseed oil is because the additives make it look like boiling - this contradicts the article but I believe the article is wrong. One of the traditional additives was lead, but even the modern lead free versions are not all that safe for food unless the manufacture claims otherwise (most don't)

You can still get actual "proper" double boiled linseed oil. It's not even especially expensive, just mildly annoying to source. It's a surprisingly durable finish for outdoor furniture etc, just takes an age to cure compared to the chemically boiled linseed oil.

Could you deep fry the spoons in your oil of choice? Imagine a commercial fry cook from a fast food restaurant. The heat would open the wood pores there by removing moisture content replaced with penetrant from the oil bath. Remove, let cool, and wipe off. In theory I don't believe there's anything wrong with the idea.

Deep frying works well when the oil is held well above water's boiling point, keeping excessive amounts of oil from soaking in because steam escaping from the food keeps excessive oil from entering. That doesn't work with wood.

That's exactly why it will work great, allowing deep oil penetration, no?

Aha, I think I get the confusion. Deep oil penetration is easy. The problem is not filling every pore (void) with resin. I mean, you can do that if you want, look up PEG https://www.rockler.com/polyethylene-glycol-peg-green-wood-s...

But usually you don't want to. The pores and void structures are part of what makes wood, wood. If you managed to fill everything with polymers then what you have is cellulose-fiber-reinforced plastic and not really what people mean when they talk about "wood". (Wood being a tangled, but directed mess of cellulose fibers lightly glued with lignin)

What you're trying to do with finishes is coat the surfaces with just a little more even of a layer of polymer; that includes the pores too, but just their surface and not their volume. Wood had good wicking action and will evenly distribute oil (or water) on its own. If you tried deep frying, you don't have enough time for the oil to evenly distribute.

As a hobbyist woodworker, I've been wondering how to protect my projects. I need to try this, great idea, thanks for sharing.

Just make sure it's a linseed oil without dryer's; they're usually heavy metal compounds.

Absolutely, very good of you to add. The idea of using a drying/boiled linseed oil did not occur to me till now, and the idea is equal parts funny and scary to entertain. Would a wood utensil soaked with wet drying oil even survive the toasting process without turning the oven - and my shop - into an impromptu fireplace? If it did make it, would the heavy metals and charred surface oils add off-flavors to my stew?

Just a heads up, rags used with raw linseed oil will ignite if you aren't careful with them. People say that only the rags used with boiled linseed oil will start fires, but I've seen rags used with raw oil ignite on two occasions.

Also...most linseed coatings will mold if they're not kept dry. If you'd like to avoid that, look for purified linseed oil -- it's regular linseed oil, but the proteins that mold feeds on have been removed. If you really want to go crazy, look for the stuff made from food grade oil.

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