First warranty claim! Photos

[Apex Predator]

One of my buddies, who I built a mild D/R longbow for over two years ago, brought his bow for me to look at.  He had some concerns about some air bubble type visual defects recently appearing under the glass.  These were in a cluster over about an inch long across the limb face.  These are on the bows back about 3" past the end of the fadeout.  They appeared to be bubbles under the glass until I inspected them very closely.  The largest is about half the size of the end of a pencil eraser.  If the bow is held with the defect facing up and is then moved around causing the surface to change angles in relation to the viewer, the spots shift over the grain of the veneers.  It's now obvious that the defects are towards the top of the glass skin lam, instead of between glass and veneer.  The Fullerplast finish is still perfect, with no blemish felt or seen.  This bow is almost 2 1/2 years old, and has probably had 2,500 arrows through her.  I've never seen this and was wondering if any of my buddies had.  He is supposed to be taking some photos for me, and I will post them.

[Savage]

So the bubbles are not in the glue?

[JamesV]

I built myself a R/D long bow with clear glass over zebra wood. Had a few specks in the lower limb, about the size of a pin head and smaller. Not really noticeable but I knew it was there. I posted it here and got a very wide range of opinions. After final sanding I found the problem, one of the bigger specks was on the edge of the limb and you could see it was in the center of the glass not between the glass and veneer as I first thought. I have shot this bow a lot and it hasn't changed any.

James................

[Savage]

Could the epoxy develop bubbles during the curing process if the oven temp is too high?

[Apex Predator]

The epoxy will boil if you get it too hot.  This is definitely inside the glass, not the glue line.

[Savage]

That's strange. I'm wondering if it came like that from the manufacturer? Seems like that would be hard to detect when you're putting it together since you cant really get a good look at the glass with the rough finish.

[Inuumarue]

Might be an internal shear failure inside the glass.  Small crack started then expanded.  If it grows between fiber layers in the glass it could look like a bubble. Dose the bubble shrink when the bow is drawn?  Thinking aloud, never had anything like it.

Adam

[HMlongbow]

I have seen this as well and John of Old Mastercrafters thinks it to be something with the glass fibers and not with glueing of bow.  It happens sometimes and there isn't really anything you can do.

[Apex Predator]

Here are some photos!  The first is a straight-on angle.  The second and third show opposite angles across the limb.  The way the spots shift over the zebra grain tells me that these are not at the laminated joint, but rather up into the top levels of the glass itself.  What do you folks think?

 

 
 

I'm thinking maybe the finish is seperating, even though there are no noticeable bulges?  I guess I should pick at them and see what happens.

[DEATHMASTER]

That does look like the finish.
Pick and find out.
May be a "easy" fix.

[Trux Turning]

Yea-it does look like it could just be the finish-be interesting to hear if it really is.

[Art B]

Is that a crack in the glass in that one spot? Could that be caused from a dry fire..........or shooting very light arrows?

Have seen something similar in a glass bow where to light an arrow was used.........Art

[Spindrift]

i know glassing bows and boats is a huge difference, but up here sometime we have problems with glass delaminating, due to resin not penetrating the glass well enough.. also oil could have been drawn out of the wood if the resin was mixed hot.. epoxy would still bind, but would be weak, and after awhile might delaminate.. just my guess, im no bowyer but up here we have alot of boats..and fiberglass

[GREG IN MALAD]

That looks like the finish peeling off. I had that happen with Fullerplast, which is the reason I stopped using it.

[hova]

looks identical to the one from about a month ago , where it was considered to be frets. the second pic you can see the fret , i bet the little bubbles have em too you just can see em.


ill see if i can find that post , its probably at page 59 now...

[7 Lakes]

Could have been a drop of sweat hitting the glass just as the spraying started.  Maybe a drop of water off the bottom of a bottle.  Hard to tell but it looks like a finish problem.  

Time to lightly sand it down to the glass and see.

[D]

It does kinda look like its in the finish but it also looks like frets as Hova was taling about.  I think that one was over some purple heart not zebra but the spots or defects definatly look that same.  I hope its not frets and just in the finish

[Holm-Made]

The first glass bow I ever built, years ago, I didn't sand the glass.  I just sprayed spar urethane on the smooth surface.  After awhile the finish lifted in the same area as that bow.  It looked similiar to what you have going on there.  Chad

[legends1]

I had a limb do that, looked just like that few years back.It was small spots in the finish that had hardend up to much.If you are off just a little with the hardener with the fullerplast it gets hard spots in it that dosnt set well on the glass.Then when the limb gets wet the water will make its way into the small openings in the finish causing those spots.Sanding the finish off and respray will fix it.

[Apex Predator]

Sorry about the delay guys!  Tonight after work didn't happen.    

These spots sanded right out.  They were definitely under the first coat of fullerplast, right next to the glass.  You guys ever try to spot re-finish a limb?  The fullerplast directions say to lightly sand before re-spraying.  I can take down the finish on the whole bow, but it would obviously take much more work.

This bow is over two years old, and technially out of warranty, but belongs to a good buddy.

I appreciate the opinions!