mold on my wood block table

I accidentally left an avocado on my wood block table. The avocado went bad and now there is a small spot that I think might be mold on my table. I'm not sure what else it would be. I have been sanding the table to try to get rid of it. I'm nervous about it spreading. I've sanded quite a bit but there is still some discoloration. Do I need to keep sanding until it's gone or is the discoloration a natural and harmless occurrence given what happened? The spot is rather light and a little smaller than a quarter. I have John Boos Mystery Oil for the table. Will that help prevent the spreading of any mold, etc?
Thanks in advance for your help!

Julie Curry


Uncle J. August 7, 2016
I wouldn't worry about it. Many things can discolor wood. Bleach is a good idea from a hygienic standpoint.
Oil is useless in this context, wood doesn't need it. It won't keep wood from cracking. Oil on wood is
for appearance only. If anything it will feed the mold. Boos' website says its a mixture of mineral oil and beeswax. The price must come from the "mystery", not the ingredients.
Smaug August 8, 2016
Not true at all about oil on wood. The light mineral oils used for counters and salad bowls doesn't offer much protection, but some of it will be absorbed and it will reduce water penetration, particularly if moisture is wiped up quickly. Heavier oils used for furniture finishing- mostly based on boiled linseed oil or tung oil, can offer a great deal of protection. I use General Finishes Outdoor Oil, which has a very high solids content, a lot on outdoor furniture- even porous softwoods can be made nearly waterproof. Oil finishes need to be renewed regularly, as expansion and contraction of the wood will constantly open up new pores. Oils can be used to produce a surface finish, though not a very durable one.
Uncle J. August 8, 2016
I stand by my answer. Neither mineral oil nor beeswax do much to repel water, while water pretty effectively displaces oil. The oil-based finishes you mention are mixed with chemicals which are not food safe (and probably taste pretty bad, too). I use oil on furniture for its appearance and feel, but certainly not for protection from water.
Smaug August 8, 2016
The oils I mention are not intended for use with food, and are likely to contain organic solvents. They are, however, the only way to effectively protect outdoor furniture, unless you feel like using spar varnish or some such, in which case you will have to strip and refinish every few months. (Polymerizing) oil finishes in combination with wax can be a very effective indoor finish for objects that don't see a lot of wear- they will protect from spills long enough to clean them up, but not much more. That's really as much moisture protection as you get from common finishes such as nitrocellulose lacquer and shellac, which will be ruined by extensive contact with water- even polyurethanes are far from impermeable, particularly to vapor. They will offer more physical protection from abrasion and heavy handling.
Smaug August 6, 2016
I would actually be very cautious about sanding a wooden surface, especially spot sanding such as this-it tends to produce low spots, which then accumulate moisture and other things and can become an ongoing problem. Bleach will kill anything, though obviously to be used with caution. A baking soda solution might do it- the main thing is to be consistent about keeping it dry. The light oils used on counters (I'm not familiar with Mr. Boos) offer some protection from moisture, but not a lot. The spot won't spread, even if alive, without some moisture to grow on.
PHIL August 6, 2016
It's probably just a stain from the avocado oil take Pierino's suggestion.
pierino August 6, 2016
I wouldn't worry about it too much but normal maintenance should include mixing a small amount of bleach with water and rubbing the table down with this. This is the sanitizing solution that restaurants use.
Julie C. August 6, 2016
Sounds good! Thank you!
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