Just discovered this…

[wood carver 2]

I picked up my little Ambush recurve and I was kind of shocked to find cracks in the glass on the backs of both limbs. I haven’t shot this bow in a while and it’s been hanging vertically on my bow rack. Here’s the bottom limb.

And the top.

I can easily feel the cracks. In fact, it seems like the glass is is raised a bit at the cracks, kind of like a pressure crack on a frozen lake.
Sorry for the dumb analogy, I couldn’t think of anything else. 🤔
I don’t know what could have caused this. The bow is only ever strung using a stringer and it has never been roughed up. Here is the bow. 54” and 52# @ 28”.

Dave.

[Kirkll]

The answer is the MC level in the bow has changed. And that action wood riser swelled up, then shrank again leaving the crack. I'm quite certain if you filled that crack with water thin super glue a couple times and let it set, you could save the bow..... or not....Its worth a shot. If nothing else, add an overlay....

I've seen this happen when bows were stored in the basement with a furnace, and dried the wood out excessively. This happens on all kinds of wood too..... Or someone has moved to a drier climate..... Wood moves with humidity levels changing....   .02 cents worth...

[wood carver 2]

Thanks for confirming what I was thinking. My bows used to be stored in the basement, but with a dehumidifier running nearby. They have been on the main floor now for at least 5 years.
So, glass bows can still absorb water even though they are sealed? I know that a glass boat can absorb water, but I thought that it would be next to impossible to suck up much water from the air.
Assuming it is able to take up enough superglue, would it still be a safe bow to shoot? This little recurve is a sweet shooter. It would be a shame to hang it up for good.
Dave.

[Kirkll]

You should be fine shooting it after that super glue dries and cures out 24 hours..... You bet bows soak up water from the air regardless of how well they are sealed.... I build my bows here in Oregon and every stick of lumber in my shop is 12% in winter time. Even if i buy bone dry KD wood at 9% , after it sets in the shop for two weeks it will test at 12% on the top.  I need to bring my freshly laid up risers into my spray booth that i keep heated to get the MC levels down before i work with them. Even after a riser has sanding sealer and its shaped, i let it set a couple days at 80 degrees before finishing, and a lot of them develop checks or small cracks that need to be filled before finishing.... When i'm sending a bow to the dry climates like NM, Texas,Arizona, Nevada... etc...etc... I'll sometimes put the finished riser in my hot box at 100 degrees for a day to make damn sure its dry....  This is critical using G-10 in a riser.... I've had quite a few come back for crack repair that i didn't get dry enough.

I had a Black & White ebony bow i built in 2012 that stayed perfect for 11 years until the guy moved into a place with gas heat that was much drier heat, and it checked in several spots. I was able to get them filled in and refinished the bow with no problem... But it happens....  The same thing will happen to fine furniture sometimes when people move.

Kirk

[wood carver 2]

This winter was warmer and wetter than usual. I sometimes feel a chill inside the house even with the heat set at 70F. Never happened during a normal, cold and relatively dry winter. Nice thing about building wood and bamboo bows is they can breathe.
We need to get back into an ice age cycle. 😁
Thanks Kirk.
Dave.

[MUZZLEBOW]

Man, that stinks. I had the same problem occur several years ago with an RER Arroyo recurve Kevin Termaat built me. I was all Macassar Ebony with Yew cores. Kevin glued an overlay over area which looked good and I didn’t have anymore issues with it. I live in North Florida were the humidity is always high. It’s still a shooter to this day.