Thread: What is Tannins?

G'day DSEL74,
I don't now how to wash out or bleach tannins.......but someone here will.
My 2 cents worth to explain a little of what tannins do is:
They make red wine taste Goood!
They are used as a mordant when dying timber darker than original.
examples are:
Brush with warm tannic acid solution....then brush with "liquid Nightmare"...makes timber dye black.
Brush with warm tannic acid solution....then brush with Ferrous Sulphate.solution.....makes timber dye black with green under-tones.
So I'd imagine in a blonde timber (such as you want to use) you would have to wash tannins out if you wished to keep it light coloured.
How this explains some of it.....there'll be someone here who knows the ins & outs of it.

Tannin is the chemical in plants that stain things brown. Tea is an example. It is in a lot of timbers. Some are more of a problem than others. It can show up if the timber gets wet. Hope this quick explanation helps.

This is tannin and what it can do!

G,day Harry. Do you intend to park under your deck again?

aww, buga!

Pity about your ride Harry!

So how do you prevent tannis from leeching out of timber after you have built a piece from it. I was planning on leaving my project natural so the timber breaths and doesn't hold moisture in. Thus making it less likely to corrode the precious metal antiques inside. However I don't want them getting stainned or the carpet.

ideas?

Artme, wasnt parked under a deck... had wood from the last "Hardwood sale on again"
on the ladder racks and it rained on that night, I had it covered with tarps but not good enough

Originally Posted by Harry72

This is tannin and what it can do!

Tannin is a natural product occurring in most all parts of trees, shrubs bushes, etc. We see it as the dark coloration in wood products. If you lay a maple leaf on the driveway or sidewalk and keep it wet for a while, the tannin will leach out and stain the concrete. You will see the outline of the leaf. If you pile a bunch of bark (mulch) on the driveway, it will stain. Same with a chip pile from the lathe or sawdust pile from the table saw. The moisture causes the tannin to be released.
Tannin that is allowed to leach out and collect will form a mild acid, hence Tannic Acid. (the acid form is used to make leather, Native American Indians used to lay deer hides in layers with oak bark and wet the whole affair....the tannic acid that leached out of the bark and into the hides would act as a preservative and coloring agent...Buckskin) Working with Tannin rich lumber will darken the skin, especially if the wood is wet. As far as neutralizing the tannin before finishing??? Commercial bleach products (especially the 2 part chlorine/peroxide) will remove the tannin, AND the color. Think about that if you want to bleach walnut??
I live in an area that is rich in Paulownia, I have turned several bowls from a large timber that was given to me. I have made several projects from sawmill boards that I ended up with. I have had absolutely no problems finishing this wood. The bowls were finished with tung oil, I made one canoe paddle from paulownia, polyurethane finish on that one...still paddling.
If you want pics of the wood, let me know??

Here is the email response I got from
<TABLE cellSpacing=0 cellPadding=0><TBODY><TR><TD>World Paulownia Institute, LLC ([email protected])
When I asked about tannis and how it is managed in their timber cutting and drying etc. What can you expect from americans who as usual call their organisation world then look down on the rest of it.
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</TD><TD></TD></TR><TR><TD class=SecondaryTextColor></TD><TD></TD></TR></TBODY></TABLE>
<TABLE cellSpacing=0 cellPadding=0><TBODY><TR><TD class=ReadMsgSubject colSpan=2>Re: tannis‏</TD></TR><TR><TD class=SecondaryTextColor>From:</TD><TD>World Paulownia Institute, LLC ([email protected])</TD></TR><TR><TD class=SecondaryTextColor>Sent:</TD><TD>Friday, 14 December 2007 10:51:35 PM</TD></TR><TR><TD class=SecondaryTextColor>To: </TD><TD>Dale Schafer ([email protected])</TD></TR></TBODY></TABLE>
Thank you for your email.
In answer to your questions it would be helpful to let us know the source of your information and your location or country.

I am not sure who is coming up with this information, maybe it is a forum and people just talking ??

However, we do not have that problem. Never have and I actually do not know that term you are using. Maybe they are cutting the timber at the wrong time of the year and the sap maybe the "tannin" ???

If you are buying timber from Australia then you need to contact them and ask them.
I am sure you looked up the definition as I did !!

Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. The term tannin refers to the use of tannins in tanning animal hides into leather; however, the term is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with proteins and other macromolecules. Tannins have molecular weights ranging from 500 to over 3,000.<SUP class=EC_reference id=EC__ref-Bate-Smith_0>[1]</SUP>

Sincerely
WPI
Customer Service
Debra







Mojack some pics would be great! Where are you located?

Nice response. Just a touch of sarcasm. Maybe we should bomb 'em.

prozac

Originally Posted by DSEL74

...<table cellpadding="0" cellspacing="0"><tbody><tr><td></td></tr><tr><td class="SecondaryTextColor"></td><td></td></tr><tr><td class="SecondaryTextColor">
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</td></tr></tbody></table>
<table cellpadding="0" cellspacing="0"><tbody><tr><td class="ReadMsgSubject" colspan="2">Re: tannis‏</td></tr><tr><td class="SecondaryTextColor">From:</td><td>World Paulownia Institute, LLC ([email protected])</td></tr><tr><td class="SecondaryTextColor">Sent:</td><td>Friday, 14 December 2007 10:51:35 PM</td></tr><tr><td class="SecondaryTextColor">To: </td><td>Dale Schafer ([email protected])</td></tr></tbody></table>
Thank you for your email.
In answer to your questions it would be helpful to let us know the source of your information and your location or country.

I am not sure who is coming up with this information, maybe it is a forum and people just talking ??

However, we do not have that problem. Never have and I actually do not know that term you are using. Maybe they are cutting the timber at the wrong time of the year and the sap maybe the "tannin" ???

If you are buying timber from Australia then you need to contact them and ask them.
I am sure you looked up the definition as I did !!

Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. The term tannin refers to the use of tannins in tanning animal hides into leather; however, the term is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with proteins and other macromolecules. Tannins have molecular weights ranging from 500 to over 3,000.<sup class="EC_reference" id="EC__ref-Bate-Smith_0">[1]</sup>

Sincerely
WPI
Customer Service
Debra....

I would have thought someone who works in Customer Service in the wood industry would have some idea of what tannins are. There was a Paulownia miller/grower around a while ago, maybe they can provide more information on the subject.

Corbs

You could have got all that from Wikipedia!