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Salad Bowl Finish on End Grain Cutting Board

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Forum topic by WolfpactVI posted 04-25-2021 01:34 PM 595 views 0 times favorited 17 replies Add to Favorites Watch
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WolfpactVI

5 posts in 60 days


04-25-2021 01:34 PM

Topic tags/keywords: question end grain finishing walnut maple cherry red heart

Hello all,

First time posting here, long, long time lurker. Hoping you can help me with a cutting board finishing problem.

I don’t get to do much woodworking right now, but I managed to squeeze in making an end grain cutting board a few weeks back. Mostly walnut, with a bit of maple, cherry and red heart. About 13×20 and 1-1/4” thick. Just a design I found on the interwebs, thought it looked cool. I’d post pics but I’m at work right now.

Anyway, after reading up on various options for finishing, including at the site I found the original design, for better or worse (worse, as it seems now) I settled on General Finishes Salad Bowl Finish with a first coat thinned 50% w/ mineral spirits to get it to penetrate as deep as possible into the end grain, with normal coats to follow. Everything seemed to go well. I let it cure 24+ hours, seemed well dry. So I put on a second undiluted coat. Just wiped it on, wiped off the excess. Did that…..Sunday or Monday night. That coat is still not dry except in one or two very small areas. Very tacky, even on the side grain on the sides. I can leave a fingerprint in it. After reading through this post here….

https://www.lumberjocks.com/topics/80233

....and other places, I first tried putting some heat and moving air on it. So I set up a little electric space heater to blow across it (not directly, about 6-8” above it) for about two days now. No change. Now I’m more than a bit worried because I read on General Finishes website here….

https://generalfinishes.com/faq/why-isnt-salad-bowl-oil-i-applied-to-walnut-serving-boards-drying-after-two-coats

....that if the first coat doesn’t dry, the second never will. Makes me think I didn’t let the first thinned coat cure completely before putting the second coat on. If that’s true, I’m in trouble. I can’t imagine a way to remove finish that’s penetrated possibly all the way through the cutting board.

So my questions are:

- if I leave it long enough, will it cure eventually?
- if not, is washing off the uncured finish with mineral spirits or acetone or something good enough to try again?
- there were many references to sanding off the uncured finish, but wouldn’t that just gum up the sandpaper? (not to mention how that would help the uncured stuff deeper in the end grain)
- is this completely ruined and do I just have to start over? I am a grown man, but I will cry if this is my only option.

Thanks in advance everyone, for any assistance you can offer!


17 replies so far

View Kelly's profile

Kelly

3595 posts in 4067 days


#1 posted 05-08-2021 04:43 AM

I’m no expert on this finish. Never used it. However, I think I’d go the route you indicate you were considering (washing the tacky finish off).

After that, I’d let it cure for a while and monitor changes to see if you’re going the right direction.

You might even try a bit of lacquer thinner in a spot, if just thinner does not work.

View OnhillWW's profile

OnhillWW

303 posts in 2355 days


#2 posted 05-08-2021 01:27 PM

Try a wipe with the same solvent you used to thin the 1st coat, maybe use a white abrasive pad to work it in and wipe off with towels. Treat both sides the same and let it dry in a warm dry environment for a week or so. You are correct that any attempt to sand it will have you screaming a George Carlin routine and ultimately get you nowhere near where you want to be. You could try a good cabinet scraper first to get the “big” stuff off then to the solvent wash.

It’s too late now but I would never have used a hardening oil on a cutting / serving board when mineral oil ( plus beeswax) based finishes are so easy and effective, not to mention inexpensive and renewable .

-- Cheap is expensive! - my Dad

View CaptainKlutz's profile

CaptainKlutz

4565 posts in 2617 days


#3 posted 05-08-2021 03:34 PM

GF Salad bowl finish (SBF) is not an oil finish, it is oil based varnish film finish.
IME- It behaves very similar to GF Arm-R-Seal polyurethane, except GF calls SBF food safe.

I would never use a film finish such as SBF, on wood service board for heavy cutting, like an end grain cutting board. It works great on decorative cheese boards or bowls where sharp knives are not involved. Sharp instruments easily cut the film, and leave scars in finish.

Has been a couple weeks since posted the issue. If the finish is going to dry/cure, and it has been stored above 75° last 2 weeks; it will be mostly cured. Anything not cured, needs to be removed. Start by scrapping the surface to remove the gummy stuff. The wash it with Paint thinner or Naphtha, using a non-woven red/gray scuff pad to remove as much as possible. Let solvent dry for couple days, and sand the board smooth. The wipe on thin film of SBF and let it cure. If you apply more than 2 coats of SBF, you will have thick plastic looking film finish.
Unless you sand the board back to bare wood, it is too late with switch to a conventional mineral oil/wax board finish.

IMHO – the mistake was likely diluting the finish with wrong MS.
If used odorless MS , or green MS; then the solvent blend was not compatible and dramatically changed cure. Need to use real Stoddard solvent, or paint thinner when diluting most varnish/poly top coats.

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

View AlaskaGuy's profile

AlaskaGuy

6639 posts in 3432 days


#4 posted 05-08-2021 03:51 PM

Charles Neil says that General Finishes Salad Bowl Finish is nothing more that a thinned down version of their Arm-R-Seal.

https://youtu.be/g2rTy3W-QEY?t=279

-- Alaskan's for Global warming!

View BurlyBob's profile (online now)

BurlyBob

9019 posts in 3389 days


#5 posted 05-08-2021 07:18 PM

I’ve used GF salad bowl finish on numerous cutting boards. Ya just had to let it firm up. My last cutting board, I had a problem. I only finished one side. This caused the board to cup, almost 1/4”. I used a lot of weight to get it back straight. From now on I elevate anything flat project and varnish both sides.

View LesB's profile

LesB

3013 posts in 4566 days


#6 posted 05-09-2021 04:54 PM

+1 for Captain Klutz’s response.

I do not think hard finishes like this should be used on a “cutting” board. They are fine on cheese boards where sharp knives won’t be marring the finish. I do use salad bowl finish on bowl and it is very durable, lasting for many years.

For my end grain cutting boards I prefer processed (heat treated) Walnut oil (Mahoneys); usually 3 applications is enough. It soaks in and polymerizes in the wood to strengthen and seal it. Like most oils does need fresh applications from time to time. It also comes with a wax added which helps resist moisture.
It is food safe and non allergenic so there is no worry about nut allergies.
Unlike mineral oil it does dry/cure in a couple of days.

-- Les B, Oregon

View Kelly's profile

Kelly

3595 posts in 4067 days


#7 posted 05-09-2021 05:01 PM

Les, as your own post notes, walnut oil is a hardening oil. As such, it is a hard finish. Just not as hard as those to which resin is added.

If heat treated, it is pre-polymerized, just as flax seed (linseed) and tung oil are.

Those things aside, yep – it’s a no for me and others regarding hard finishes on cutting boards.

The ONLY way you can get significant penetration with them is, thin the finish and keep the surface flooded (wet) for as long as possible (once you stop, and remove excess, the hardening process begins).

Of course, when the coat of hard what have you is complete, you have just another piece of Formica for a cutting board.

View WolfpactVI's profile

WolfpactVI

5 posts in 60 days


#8 posted 05-10-2021 02:34 PM

Holy smokes, I’m away from the interwebs for the weekend and I hit the jackpot. Thanks so much for all of the replies!

So the reason I selected the GF salad bowl finish was I wanted a hardening finish that would soak all he way through (or almost) and cure and harden deep into the end grain. I realize that the surface would have to be periodically renewed from all of the cutting with one of the “board butters” like the mineral oil and beeswax or walnut oil and beeswax.

From what I can tell I made at least two mistakes. First, thinning it with the possibly the wrong solvent. Or thinning it at all. I used Klean-Strip odorless mineral spirits, not realizing it might not be compatible, or affect curing time. I have also read that the oils in walnut and redheart might also affect curing of the GF salad bowl finish. Second mistake was not letting the initial thinned, soaked-in application to cure for a few weeks, rather than a day or two. In hind-sight, the salad bowl finish is so thin to begin with I probably didn’t need to thin the initial application anyway.

What I ended up doing was scrubbing the thing with the same odorless mineral spirits to get as much of the un-cured second coat off, letting it dry with gentle heat for another day or two, and sanding it. Seemed dry so I tried a third coat, wiped on and wiped off so there was no excess left on the surface. However, even after days and days it still seems slightly tacky. So does the excess finish left on my gloves and the wiping cloth for that matter. I know it’s not a matter of humidity or temperature or still air, since the dehumidifier keeps the basement at around 35% RH at all times, and I kept a small space heater blowing across it on low.

So for now I’ve given up on the GF salad bowl finish. I’m going to give the most recent coat another week or so to cure, and if anything is still tacky I’ll wipe it down with mineral spirits again, let it dry and be done. Perhaps buff on a coat of one of those board butters.

Now, I’m about to glue up a second identical board, so I have a chance to finish this one better. I’d be fine to just use mineral or walnut oil and be done, if the general consensus is that is enough of a seal for sanitary and washing purposes.

Les B, I’m certainly intrigued by the Mahoney’s Walnut Oil. I did not realize there was a curing walnut oil out there.

Kelly, I’m slightly confused by your reply to LesB. Are you saying plain walnut oil or pre-polymerized walnut oil is a good idea or not? Also, I didn’t quite catch your point in the last sentence. I’m guessing you’re recommending against a penetrating hardening finish for cutting boards. Why is that?

Thanks again everyone!

View Kelly's profile

Kelly

3595 posts in 4067 days


#9 posted 05-10-2021 04:35 PM

The traditional finish for cutting boards is non-hardening oil. As I note, it keeps wicking until the wood is saturated with it. Wood saturated with non-hardening oil will not shrink, so will not crack and split. Nor will it take oil the oils and other liquids that are associated with their use.

If you never used the board, oiling it until saturation would be the end of it, since the oil doesn’t evaporate, though you may have to deal with some oozing as the last bit of oil works its way deeper to and into the center of the wood.

Because they are used, cutting boards have to be cleaned, which removes some of the protection off the surface. When the surface is washed then dried, that same wicking action takes place in reverse. As such, the board would need a light touch up, which would be the only time you wipe off excess, other than noted below.

Since all hardening finishes harden, they seal the wood, anything after the first penetrating coat is a build on a surface coat, but which many of us would ever use on a cutting board.

Not using a hardening finish on an end grain board seems more important because you are defeating some of the value of end grain by tying all the end grain together. Remember how those spaghetti like knife holders work – you never leave a mark when you insert a knife and pull it out again.

Then there is the example of my own hands in the shop – when dry, I get slivers easily, but, if I put lotion on them, not so much. The resilience of the skin helps keep the splinters down.

Walnut oil is a hardening oil, like tung oil and linseed oils. Too, like flax-linseed oil, it can go rancid.

View WolfpactVI's profile

WolfpactVI

5 posts in 60 days


#10 posted 05-10-2021 05:41 PM

Kelly,

Thanks for your reply. So are you saying any walnut oil will eventually harden, even the food-grade stuff that’s not processed like Mahoney’s? Also, that’s interesting about the last bit – I had read the opposite, that walnut oil will not go rancid at room temperature and can be stored a long time, especially in a cooler, dark place like a cabinet.

Another aside, I re-reading the other thread, there was a comment about not sanding the end grain with higher than about 180 grit. Is that the general consensus? That’s another thing I had not heard of before. I think I went as high as 220 before the first coat.

View OSU55's profile

OSU55

2796 posts in 3113 days


#11 posted 05-11-2021 02:00 PM

The only real issue with using a hardening finish on a piece that will have utensils used on it is it will get visibly scratched/cut up. Functionally it will be fine. Mineral oil is typically used because it doesn’t show the wear, and does not become rancid like vegetable oils. Not sure whether non-heat treated walnut oil becomes rancid – a search should answer that. Mahoney’s will not, and will eventually “harden” (2-3 months), but its relatively soft.

With non or slow curing oil, the sanding grit effects how fast the oil is absorbs but not the total amount. Eventually the oil will absorb, but could take days longer. If you want a smoother look, sand to ~180, saturate the wood for several days, then wet sand to higher grits.

View LesB's profile

LesB

3013 posts in 4566 days


#12 posted 05-11-2021 05:47 PM

After re-reading things I think one of your problems is using the wrong thinning agent. General says their salad bowl is a heavy oil (mystery oil?) and urethane. Urethane takes a “special” chemical thinner NOT mineral spirits.

As you said it is so thin from the can it needs no thinning. Also a partial used can develops a thick film on the surface if you don’t remove the oxygen from the can.

-- Les B, Oregon

View OSU55's profile

OSU55

2796 posts in 3113 days


#13 posted 05-11-2021 08:03 PM



Urethane takes a “special” chemical thinner NOT mineral spirits.

- LesB

For the hi end urethanes, like for auto, this may well be true, but for wood finishes it is not. Regular mineral spirits has worked just fine for me with polyurethane varnishes and many other wood finishes containing urethane.

View WolfpactVI's profile

WolfpactVI

5 posts in 60 days


#14 posted 05-11-2021 08:34 PM

Les: Thanks for the reply. I was just following some things I read elsewhere (Wood Whisperer maybe?) and more than one place mentioned thinning with mineral spirits (including the specific kind I used). Interestingly the GF salad bowl finish has been replaced/renamed with Wood Bowl Finish. I don’t have the can in front of me, but the MSDS sheet on Woodcraft says it has Stoddard solvents in it, and the Wood Bowl Finish instructions say it can be thinned with mineral spirits. Cleanup is also with mineral spirits. So I really couldn’t say whether or not that is my issue. Especially since even the un-thinned finish in the wiping cloth and on the gloves seems to be taking forever to dry. Maybe I just got a bad batch or old can.

OSU55: try googling whether or not walnut oil will go rancid. There are about a thousand websites and posts that say it DEFINITELY will go bad in 6-12 months, or in several years (cant seem to agree), and a thousand other websites that say it will NEVER go bad. There are as many that say Mahoney’s will definitely go rancid eventually, and as many that declare it never will. Amusingly, there are an equal number of sites and posts that claim walnut oil of any variety dries/cures as there are that confidently state that it does not. At least there is consensus that mineral oil will never go rancid, though there isn’t consensus whether it’s OK because it’s petroleum-based (that one doesn’t bother me), and most amusing are the ones claiming mineral dries. <sigh>

View Kelly's profile

Kelly

3595 posts in 4067 days


#15 posted 05-12-2021 09:50 PM

It’s all about the oxidation.

It is indisputable, among those knowledgeable about such things and having reasonable minds, flax seed goes rancid. Only after it is specially treated to become “boiled” linseed oil can it be stored a long time without going rancid. At that point, it’s not really flax seed oil anymore, but it must still be protected from oxygen when stored, or it will harden.

Of course, olive oil goes rancid too. I’ve dealt, first hand, with boards on which people used olive oil, “for its healthy benefits.” However, you could smell that a problem had come out of its use, even they went on insisting olive oil was the only oil to use, because it’s natural.

Anyone who has dealt with storing walnuts in any significant amount knows they go stale (just another name for rancid), if they are left laying around for long periods. As such, it stands to reason the oil would be included as part of that problem.

_

“Nuts contain unsaturated fats that oxidize when exposed to heat, light and air, breaking the double bonds in the fat molecules. The short-chain fatty acids left behind are what make nuts rancid. The types of nuts with more of these fats, such as walnuts, pine nuts and pecans, are at a greater risk for rancidity.”

https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/nut-oils

https://www.sciencedirect.com/topics/engineering/plant-oil-based-polymer

https://en.wikipedia.org/wiki/Drying_oil

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