Black Mold on wet wood

[Michael Mendelsohn]

In the past year I have received 3 batches of sweetgum logs. In all cases, the logs were freshly cut from living trees. The results were -

Tree 1 - Rough turned most of logs within 2 weeks and had no mold. Left one log outside under cover for a three of months and it turned black.

Tree 2 - Rough turned all wood within a week. Logs were clean when turned but formed mold while drying

Tree 3 - Rough turned half of wood within a week. Mold formed on turned bowls and remaining logs about a week later.

The first tree was cut in early winter, the second in the spring and the last in late summer.

I haven't had problems with other kinds of wood. Is this a characteristic of Sweetgum? Is time of year tree was cut a factor?

Any ideas of how to prevent this mold or should I just give up on sweetgum?

 

[Mark Mandell]

In the past year I have received 3 batches of sweetgum logs. In all cases, the logs were freshly cut from living trees. The results were -

Tree 1 - Rough turned most of logs within 2 weeks and had no mold. Left one log outside under cover for a three of months and it turned black.

Tree 2 - Rough turned all wood within a week. Logs were clean when turned but formed mold while drying

Tree 3 - Rough turned half of wood within a week. Mold formed on turned bowls and remaining logs about a week later.

The first tree was cut in early winter, the second in the spring and the last in late summer.

I haven't had problems with other kinds of wood. Is this a characteristic of Sweetgum? Is time of year tree was cut a factor?

Any ideas of how to prevent this mold or should I just give up on sweetgum?

Molds grow from spores which "land" on the wood surface. They are everywhere in the environment. Easy way to kill the spores is to wet the log or the rough-turned surfaces with chlorine bleach. I do this after milling my lumber and before stacking to dry. Goes a long way to preventing sticker stain and should prevent your problem with turnings. If leaving the logs outside, I'd try to tarp them and re-bleach from time-to-time.

 

[hockenbery]

You are probably turning too many bowls to make the paper bag drying feasible.
In the paper bag method, I check the bowls every day for 5-7 days an replace damp bags with dry ones.
Any sign of mold and I wipe the bowls with Clorox and discard the bags.
After the bowls are not giving off moisture the surface is too dry grow mold.
Once the bags are dry I stores the bowls in the bag on their side.

Removing the bark before storing the logs and washing the rough turned bowl with soap and water will reduce the chances of mold developing.
Mold needs moisture.

Also one moldy bowl will infect
Stack the bowls open down not nested or on their sides not nested.

 

[Dale Miner]

Molds grow from spores which "land" on the wood surface. They are everywhere in the environment. Easy way to kill the spores is to wet the log or the rough-turned surfaces with chlorine bleach.

Fungus (mold) won't grow on wood with a moisture content below a certain point, somewhere around 18%. Getting the wood's moisture level below that point as soon as possible minimizes the opportunity for fungal activity. But, there is a fine line between drying rapid enough to prevent fungal activity and drying so fast that the wood cracks.

If the wood is treated with something that makes an environment that is hostile to spores, then the need for rapid drying is lessened. While bleach does kill the spores that come in contact with it, I have found it to be only marginal at best in preventing mold and fungal degrade of rough outs.

My reasoning:

Bleach is a low concentration of chlorine in a water based solution. The chlorine in bleach leaves the solution in a day or two after application. The water in the solution remains after the chlorine has left, and during the time the water in the solution is evaporating, the moisture content of the wood remains at the level it was prior to applying the bleach. So while the spores that are on the wood and land on the wood while the chlorine is active are killed, the spores that land on the wood after the chlorine leaves find an environment that is at least as favorable for growth as before the application of the bleach.

My process:

On rough outs from woods that are prone to mold or fungal discoloration, I treat the surface of the rough out with a solution of boric acid disolved in warm water. Boric acid is toxic to fungus and the boric acid kills any spores that are on the surface of the rough out. While the solution does add water to the rough out, the boric acid does not leave the surface of the rough out. When the water does evaporate, the boric acid remains and creates a hostile environment for fungal activity.

Boric acid does pose a very low threat to human health, but the quantity needed for health concerns is way beyond anything that would be encountered in the process. It does seem to me that rough outs treated with boric acid dull tooling faster than untreated until the surface of the wood has been removed. After the top surface has been removed there does not seem to be any difference in edge life.

I use a concentration of about a teaspoon per cup of water. Warm water dissolves the boric acid faster than cold.

 

[Bill Boehme]

Is the mold a problem?

I bought a bunch of ambrosia maple blanks at SWAT. I found that the wood was quite wet while rough turning it. I coated them with Anchorseal and within a week there were large splotches of black on some of the pieces. My first thought is that I had applied too much Anchorseal and it was trapping the moisture although weighing them shows that they are losing moisture reasonably well. I had assumed that the mold was only on the surface since I have never encountered this situation before. Does the mold stain penetrate deeply? These bowels are destined for the Empty Bowls Project in Fort Worth.

 

[Michael Mendelsohn]

In my case the mold seems to follow the cells of the wood and penetrate along the length of the log. In the case of the rough turnings, the mold shows on both the inside and outside of the bowl.

Is there any way to clean up wood that is already moldy? Otherwise I have 4 logs ready to burn or dump.

 

[hockenbery]

I bought a bunch of ambrosia maple blanks at SWAT. I found that the wood was quite wet while rough turning it. I coated them with Anchorseal and within a week there were large splotches of black on some of the pieces. My first thought is that I had applied too much Anchorseal and it was trapping the moisture although weighing them shows that they are losing moisture reasonably well. I had assumed that the mold was only on the surface since I have never encountered this situation before. Does the mold stain penetrate deeply? These bowels are destined for the Empty Bowls Project in Fort Worth.

Bill,
I have never seen mold leave an improvement. And bleaching has minimal affect on mold. It also turns ambrosia an eerie green.

If your roughouts were turned with balanced grain and you remount them with the rim lined up there will be two lines on the outside where you do not need to turn any wood away. So any mold close to these lines will be showing when the bowl is round and ready for shear scraping. You may have enough wood to turn a1/4" away and that may get the stain. The mold may discolor quite deeply in places and you may not get it all.

Black Leather dye will hide the mold and the ambrosia too. While this may seem like an awful solution. A bowl with a nice shape and maybe some texturing can look spectacular. You are the only one who is suspecting the beautiful ambrosia pattern. If you lose it to mold consider dye as one alternative for producing a spectacular bowl.

Al

 

[robo hippy]

Well, I was told once that Sweet Gum is related to the maples, but the Latin name doesn't have Acer in it, so not sure about that. It does spault very quickly like the maples can, and that can be because of a higher sugar content when compared to other trees. If there is not enough air circulation, they can mold very quickly as they prefer moist to dry. I will have to ask a friend who had some maple bowls that molded under the plastic stretch film. He did floors for years, and has some 'industrial' wood bleach, and was going to use that to see if it would take the mold out.

robo hippy

 

[hockenbery]

Here is a photo of 2 part woodbleach (Kleanstrip) on an ambrosia maple HF I do not like the effect.
Even sanded back some the rich warm brown of the ambrosia is lost and the bleached ambrosia has a cold green cast to it.

And Fiebings USMC black dye on a not so pretty cherry ball.
The dye brings out the texture.

Check out Mark Gardner's work. He is a master with this dye.
Subtle texture made to shine with the black.

Al

 

[Shawn Pachlhofer]

mold or....?

sweet gum seems to very plain, creamy yellowish white.

I have 2 halves of the same log, cut in January this year. I sawed them round, then wrapped in plastic wrap and set them aside...for 8 months.

below are photos of wrapped log, unwrapped, and large NE bowl I turned.

I don't know if it's spalting, or if it's due to the sap in the wood.

based on the coloration of this piece - I'm leaving the other piece wrapped for another month or so, then will turn it.

 

[Bill Boehme]

Bill,
I have never seen mold leave an improvement. And bleaching has minimal affect on mold. It also turns ambrosia an eerie green.

If your roughouts were turned with balanced grain and you remount them with the rim lined up there will be two lines on the outside where you do not need to turn any wood away. So any mold close to these lines will be showing when the bowl is round and ready for shear scraping. You may have enough wood to turn a1/4" away and that may get the stain. The mold may discolor quite deeply in places and you may not get it all.

Black Leather dye will hide the mold and the ambrosia too. While this may seem like an awful solution. A bowl with a nice shape and maybe some texturing can look spectacular. You are the only one who is suspecting the beautiful ambrosia pattern. If you lose it to mold consider dye as one alternative for producing a spectacular bowl.

Al

I could always do what I did last year using silver Rub 'n Buff and then aniline dye. I was just playing around different effect on an ugly bowl and the results was much better than I expected. I then applied pickling stain to the interior. I was surprised that they actually moved it from the other bowls to the "bump" area.

 

[hockenbery]

I could always do what I did last year using silver Rub 'n Buff and then aniline dye. I was just playing around different effect on an ugly bowl and the results was much better than I expected. I then applied pickling stain to the interior. I was surprised that they actually moved it from the other bowls to the "bump" area. <img src="http://www.aawforum.org/vbforum/attachment.php?attachmentid=7891"/>

You could!
Color is a great way to dress up disappointing wood