G/flex question

Robber58

Robber58

Joined
Oct 9, 2008
Messages
478
I decided to try G/flex after years of using acraglas based upon comments and recommendations on this and other forums. I did a couple of test pieces to make certain I was mixing and applying correctly and they seemed fine. It is indeed flexible. However, I glued up a handle last night and today the epoxy seems hard but there is a tacky film on the surface. The residual I had in a small cup shows the same characteristics; a hard, solid mass with a tacky surface. I threw away the test pieces so I don't have them to check but I do not recall that tacky surface. This has me baffled since it does seems hard and strong. In fact, I worked a small lump loose from the ironwood handle and it came away with a bit of wood attached. However, the sticky surface reminds me of a knife years ago where the epoxy did not cure. It was sticky but also soft, unlike this situation. Has anyone had any similar experiences with this stuff?
Randy
 
I've noticed that seems to happen when the ambient temp. is on the cool side.
In winter, after it tacks up a bit, I leave the knife on top of the base board to cure overnight. Next morning, no tackiness.
 
Thanks for the input. It is a bit cool and I did let it sit in the shop to set some before bringing it in to the house for the night. My wife does keep things cooler than I like so I may just need to let it go another day. I put it under a warm light in my leather room so I will see what I have tomorrow.
Randy
 
We mix this stuff at work every day for years, so we've messed it up just about every way possible by now. We've seen this effect from improper ratios of mixed ingredients as well as inadequate mix time. Make sure you fully mix for at minimum one minute.
 
Heat it up and it should be fine. I put my glued up handles in the same room with our wood stove, and leave overnight. The next day there is no tacky film.
 
In the summer time I will generally work with a knife within 8 to 10 hours. However, in the winter I will let the G-Flex cure for 24 to 48. After about 6 hours I can still cut it with a utility knife to trim the excess in the winter. In the summer I do this trimming after about an hour and a half.
 
Thanks to all for the input. I do measure very carefully and mix for 3 to 4 minutes so I am comfortable those variables should not be an issue. Hopefully, time and a bit more heat will do it.
Randy
 
One thing I do in the winter months is I have one of those metal shop lights, put a regular bulb (not one of those curly cue things) so it acts like a mild heat lamp. Put the blade about a foot away and it gets it just right it seems. Over night and it is ready to go. Well plus the proper ratio and mixing.
 
The mixing thing can cause that situation and was mentioned. Do you just sort of swirl ,the two parts together? Folding the parts together is far more reliable. Frank
 
Frank,
When I mix I use a small plastic cup from Brownells with measure marks on the side to get the volume ratio correct. I use a craft stick and a variety of motions over a minimum of 3 minutes to ensure it is well blended. This was a bit bigger batch so I actually mixed for close to 5 minutes. It is better this morning after a night under a 60 watt bulb so it does not look like I will not have to attempt to take it apart. That would have been a pain with nice ironwood against steel bolsters. The only other time I have ever had anything like this happen was years ago with old epoxy that would simply not cure at all. This is new stuff from a good supplier so I don't think that was the issue. I will have to do some more testing to see if I can figure out just what is going on. It may just be temperature because the first 24 hours it was in the low 40's in my shop and only 64 in the house (my wife likes it cool at night). I do know that temperature can have a dramatic effect on curing times.
Thanks for all the help guys.
Randy
 
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