Unusual Grain in White Ash

An example of "tiger stripe" in an Ash board. August 31, 2009

Iím curious as to if anybody has seen this before or knows what would cause the annual rings to expand, compress and appear to flow into and out of each other. There is some curl that runs almost perfectly lengthwise in the QS pieces. Many of our guys have suggestions but nobody knows for sure. The tree came from north central Pennsylvania and a second tree standing on the same tract has nearly identical grain patterns!

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Forum Responses
(Sawing and Drying Forum)
From contributor T:
Curly grain on quartersawn pieces that runs almost parallel to the length of the board is generally "ribbon figure" seen in mahogany, gum, elms, and sometimes hickory. As far as I know it only comes from interlocked grain, and I have never heard of ash doing such a thing, ash splits very easily. Sometimes trees that are unhealthy or dying do strange things in distress, but in these cases spiral grains only occur in the last inch or two of growth. Was this a healthy tree? Maybe something was going on in the root system distressing it? I have seen this a lot in large oak trees where it is very common. Iím not sure what is going on here, but hope this helps.

From contributor D:
I run a lot of ash flooring in PA and have seen tigerstripe grain in ash many times. As you say it is mostly in pieces that have come out quartersawn. I do not know what causes it. Last summer I cut out a muzzleloader stock blank for a customer out of ash. It was extremely tigerstriped like you generally see in maple.

From contributor M:
Looks like "fraxinus oliva" which doesn't exist really. Ash contaminated by a mushroom has this type of figure, and even worse like the picture below.

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