Alcohol problems

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William Roscoe

New User
William
I wanted to tint a bowl so I poured about 20ml of alcohol in the bowl and put 1 drop of transtint in it and mixed it up and then brushed it on the inside. First thing that happened was a big crack opened up on the endgrain. Then I noticed the tint was already on the outside of the bowl on the endgrain sides. Amazing how it traveled thru the wood so fast!! I finished the outside surfaces and let it dry for about 30 min and the crack went back together. Maybe next time I should mix the transtint in a separate container. I do like using the alcohol, though but I need to practice more. Any other obvious mistakes you think I should know about before trying again?
 

KenOfCary

Ken
Staff member
Corporate Member
A little too much alcohol saturation going on there - but you figured that out yourself. Applied with a foam brush it should be easier to control.
 

KenOfCary

Ken
Staff member
Corporate Member
Nah, Alcohol fumes are not toxic. And not that volatile. I have a gas heater in the corner of my shop and worry about some flammable vapors reaching the flame. No pilot, but you never know when the ignition might lite.

For instance, I will not use contact cement in the shop - take it out on the porch if I have to use it. But I digress.
 

Jim Wallace

jimwallacewoodturning.com
Jim
Corporate Member
So what about the crack? Do you think the alcohol sucked up whatever water was stored in the end grain causing (the end grain cells to shrink, causing) the crack? Did it go back because as the alcohol evaporated it left the water behind or did the wood take moisture back from the air? Finally, once the crack appears, it would seem that the lignin bond between the cells is broken. That can't repair itself can it? So, if exposed to dry conditions (like many houses in winter), is it likely to reappear or not?
 

Jeff

New User
Jeff
A few thoughts to consider.

1. What is the wood species used in this bowl and is the bowl free of pith wood in the original blank?

2. End grain is like a bundle of straws whose openings can be pretty open. The classic example is red vs. white oak.

http://www.wood-database.com/wood-articles/distinguishing-red-oak-from-white-oak/

So an open end grain wood may quickly transmit the dye solution to the exterior of the bowl. It'd be better to pre-mix the dye/alcohol separately and swab it on with a rag. Then wipe it off.

3. The rapid cracking and self-mending is mysterious. Rough turned bowls are often soaked in alcohol to speed up the drying process but that doesn't appear to be detrimental.

http://www.woodcentral.com/articles/turning/articles_473.shtml
 

BWSmith

New User
BW
Endless,thats exactly what I was thinking,haha.But hey,didn't he get #1,by admitting he has a problem?
 

William Roscoe

New User
William
The wood was gum and it was about 3/16 thick. I was proud that I was able to turn this bowl with the pith still intact and no cracks. It was dry so the alcohol went threw too quickly and split and opened up about a quarter of an inch gap. I almost got my sledge hammer and did the Gallager trick on it but instead I did some other things and when I came back, it was back to just a hair line crack.
 

Jeff

New User
Jeff
Did the dye telegraph through just the cracked area or the entire exterior surface? I'm guessing that the cracked area is the darker heartwood which contains the pith. How about a few pics?

Sweet gum is notorious for twisting/warping/cracking during and after drying so that's what you may have observed with the alcohol.

http://www.hobbithouseinc.com/personal/woodpics/gum.htm

Here's an interesting discussion which includes sweet gum as a bad actor.

http://www.woodturningvideosplus.com/boiling-green-wood.html
 

SubGuy

Administrator
Zach
Alcohol will absorb water and replace it in a medium. It also has a very low boiling point and will evaporate and pull out water with it. I suspect your crack developed because what water was in the wood (the 10-15% MC) was displaced and caused shrinkage. Once the atmosphere replaced the water in the wood and the alcohol was evaporated, the wood turned back into it's original shape and closed the gap. I believe this was exaggerated in the end grain because the water was able to move more easily in that portion of the wood. This is my theory based off of my understanding of alcohol.

I have used alcohol to displace water in electronics and assist in the evaporation of that water. Someone else may chime in and address this more scientifically.
 

William Roscoe

New User
William
The bowl was 6% MC when I put the alcohol in and the end grain on opposing sides of this bowl sucked up the alcohol so fast that it had to crack in order to displace the extra volume of wood. The stain only came thru on the 2 end grain sections.
 

Jim Wallace

jimwallacewoodturning.com
Jim
Corporate Member
I think you're saying the opposite of what we're hypothesizing. You're saying that the wood was dry and absorbed the alcohol so quickly that expansion caused it to crack. What we're theorizing (I say that because for me, at least, it's just a little better than a guess) is that the alcohol sucked the remaining water out of the cells so they shrank causing the crack.
 

Rick M

New User
Rick
I agree with William. The wood absorbed the liquid very quickly and expanded.

I mix dye in a spray bottle and just spritz it on until I have the color I want.

Sent from my T-Mobile G2 using Tapatalk 2
 

William Roscoe

New User
William
This bone dry gum bowl absorbed so much alcohol on 2 sides of the bowl (end grains), but not the 2 flat grain sides, it expanded and cracked. Alcohol evaporates so fast that just a few minutes later it was all gone and the split went back together(almost completely).
 

SubGuy

Administrator
Zach
The reason I am having a hard time understanding is maybe I don't fully picture the grain structure of your bowl. It's it a bowl that grain runs from one side to the other, or from top to bottom. What direction did the crack develop in reference to the grain? Did it protrude like a (excuse me for a lack of better analogy) hemorrhoid? At this point I am trying to understand vice diagnose.
 

CrealBilly

New User
Jeff
I suspect any liquid, alcohol or otherwise absorbed by dry wood causes the wood cells to swell and if the liquid evaporates quickly it may cause the cells to collapse - resulting is checks and splits.

Ofcourse uneven evaporation will cause the same effect.

Wood species have varying percentages of safe moisture content loss per day - by exceeding the specified level - you risk introducing drying defects.
 

Jeff

New User
Jeff
Zach,

William can answer your question but here's my understanding of what he's done.

1. A sweet gum log turning blank dried to 6% MC. All is good so far.

2. View the blank from top to bottom vertically and the pith wood is in the very center of the heartwood.

http://www.woodstairs.com/tradepage/how-to-evaluate-wood/tree-diagram/

3. Turn the bowl with the pith wood on centers so the pith is still top to bottom of the bowl.

4. Cracks in the center emanating from the pith wood area when treated with the alcohol/dye mixture. Those self-healed on their own.
 

smallboat

smallboat
Corporate Member
Jeff- I think you need to switch the orientation 90 deg.
William describes it as having "2 sides of the bowl (end grains)" and "2 flat grain sides"
which would indicate the pith being oriented perpendicular to the turning axis.
This would also be a more typical (though not exclusive) orientation for turning a bowl.

If the pith were running top to bottom on the bowl it would be parallel to the axis on the lathe.
If the pith were located on the axis, his endgrain would be uniformly distributed around the surface of the bowl.
 
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