Page 1 of 1

urethane Hammer outgassing causing huge bubbles in plug ...

Posted: September 22nd, 2018, 5:47 am
by snick
Recently plugged the fingers on a new Hammer Urethane and noticed a steady stream of bubbles coming from one of the holes creating bubbles in the plug. Not sure where this is coming from; the plugs are only 3/4" deep. No visible core separation.

After the plug cured overnight, there was a huge mass of hardened bubbles at the top of the plug, about 1" above the surface. I cvut the plkug down and found a 3/8" very deep, smooth crater in the plug. So I poured another batch of plug into the crater, and to my surprise, the bubbles started forming again, and once the plug began to harden, two large buibbles had formed.

Anyone ever see this before?

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 22nd, 2018, 3:47 pm
by EricHartwell
I just had one of my balance holes plugged and it did the same thing just not quite as extreme. The plug material was of the quick set type and it had been sitting in the shop unused for several months. My driller apologized and would fix it when I get some of my other balls plugged. He blamed it on moisture in the base plug material. I have a lot of plug work coming in the next year. I won't be in such a hurry in the future and give him plenty of time to make the rest look good.

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 22nd, 2018, 7:49 pm
by Glenn
I had a similar event of small bubbles sometime back on one pearl bowling ball. I haven't had any repeat occurrences since I do my work in a more climate controlled environment where the room temperature is in the 70s and the relative humidity is kept about 45%. I usually leave the bowling ball in this room for a while before and after I plug it. I generally buy in smaller quantities so it is always fresher, but I recently bought in larger quantity since I will have to plug several balls because of the rule change. I once read where the ball plug material is temperature sensitive (keep it 72-78 degrees), but don't recall any cautions about humidity. However, I suspect high humidity could impact it as well. It seemed to me that some brands had a tendency to bubble more than others when curing, and aggressive stirring can introduce bubbles (but not like what you are describing).

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 22nd, 2018, 9:08 pm
by snick
I should have mentioned that I plugged two urethane balls at the same time, from the same cup of plug mixture. One ball turned out fine, the other has a volcano in the middle finger.

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 23rd, 2018, 3:33 am
by EricHartwell
snick wrote:I should have mentioned that I plugged two urethane balls at the same time, from the same cup of plug mixture. One ball turned out fine, the other has a volcano in the middle finger.
Could there have been moisture in just that one hole?

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 23rd, 2018, 8:33 am
by snick
I seriously doubt it. The holes are 1.25"x3/4" deep overlapping at the bridge.

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 23rd, 2018, 8:36 am
by snick
This is photo of the second attempt to fill the hole. The bubbles in the first pour were far more significant.
bubbles.JPG

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 24th, 2018, 7:32 pm
by georgeh
Two thoughts, first it could be an air pocket in the ball and the plug was curing and getting thicker as it replaced the air pocket. Second, I have had air bubbles in some (mostly finger) gripping holes that I attributed to the epoxy glue used on the insert/slug. BUT not a one looked quite like the one pictured.

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 25th, 2018, 1:03 am
by snick
The initial plug had a mass of large bubbles about 1" above the ball surface. Second, shown in the photo was about 1/3 as high, and the third plug finally worked. Thanks.

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 25th, 2018, 4:54 pm
by bowl1820
I dont do any plugging, but Ive read plenty of posts talking about problems others have had.

When it came to bubbles it was usually either caused by how you mixed it either too fast, too long etc.

Or moisture either in the ball or getting in the plug material jugs.

Make sure your ball is really dry and try a new bottle of plug and be really careful about mixing and see how it goes.

Re: urethane Hammer outgassing causing huge bubbles in plug

Posted: September 25th, 2018, 10:23 pm
by snick
That mixed batch of plug seemed to cure just fine in one other ball, as well as the leftover plug.
If you stir the plug vigorously for 5 minutes, it might end up with tons of tiny pinholes and a foamy top, but this alone won't create volcanic outgassing in a small area.

The holes were very shallow, with no visible evidence of moisture in the bottom. the balls were drilled and plugged in about 10 minutes.

BTW, I noticed the outgassing (stream of bubbles rising to the surface) immediately after pouring the plug while it was still cool.