I've got an issue.  I have a customer who is 56, very old school bowler, loves buying new stuff, but still brings his old reliables from the late 90s and early 2000s.  Over the last several years he's had a really tough time holding on to stuff.  Here's the real issue, he has 1/2 reverse in his thumb on a span of 4 1/2.  Here's the aggravating issue, all his old stuff he can hang onto, the new stuff he can't.  He won't let me change his fit at all, because, "well if I can hang onto my old stuff, you should be able to copy that."  He's a self admitted gripper, says he'll never change, and is just beside himself with irritation that he can't hang onto anything, and we all know who is to blame here . .  However, he's had numerous people drill for him, including some really big names in the industry, and nothing works. 

The most critical issue to me is that I can feel what he's feeling, and somehow his old balls he can hang onto have super tacky surfaces.  He uses slugs, but his old ones are polished, they're really shiny and really tacky, but they're also 15 year old slugs too.  I've tried all kinds of things to make the newer slugs tacky, I've tried wet sanding, polishing, etc., but nothing seems to work, just makes the slug slippery.  I know what the real problem and solution is here, but he wants nothing to do with it.  If he was having issues hanging onto his old stuff I could work with that, but he goes right back to them and has no problems, so in his mind it's a driller competence issue . .  I just have no clue what I can do to tack up a thumbhole, because usually that's the opposite direction that you want to go. 

Maybe massage some non-slip cream in there?  High gloss it and then do that?  Freakin pine tar?  Fishing here . .

However, he's had numerous people drill for him, including some really big names in the industry, and nothing works.

I know what the real problem and solution is here, but he wants nothing to do with it.  If he was having issues hanging onto his old stuff I could work with that, but he goes right back to them and has no problems, so in his mind it's a driller competence issue

These things make me question if you want him as a customer.  I mean really, can this type of cat be satisfied? 

vinyl slug.  if they are too slick rub some acetone on it.  anything you do to a urethane slug will make it slicker.

I'm not sure I could get away with that . . he uses urethane slugs, his old balls have urethane slugs, and he's convinced there's some way to make it work.  Like I said, won't let me change ANYTHING. 

vinyl slug.  if they are too slick rub some acetone on it.  anything you do to a urethane slug will make it slicker.

Or just reslug a ball with vinyl and tell him it's your experiment to see if it will work for him.  You aren't going to make a urethane slug tacky.

He can bicker and complain all he wants but if he wants a solution it will take some experimenting to figure it out. Or in 20 years when he is dead they should be old enough he could use them but would never know.

You can add black tape or white tape to help create a tackier surface. If he says it isn't like his old stuff tell him he is observant but neither is anything else. Blowing hot air like trying to fog a window into any slug will make it tacky. He should have no issues doing that. Eventually he will build up enough oil from his hands it may be fine.

Sanding them up with 1000 and 2000 grit sandpaper on a bevel sander will make almost any slug feel like it has been polished. You can work it up to 4000 if you like. Not sure if it will create a tackiness or not but it will shine up like polish without the residue.

The grips with the bump are Contour.  He probably wouldn't try one, but if he does be warned that you have to use a few sizes larger sleeve because of the bump.  --  JohnP

http://www.buddiesproshop.com/p-722-contour-power-grips-power-taper-thumb-sleeve-white.aspx

Might be old fashioned, but how about the old Master Cork Thumb Inserts. They still have them.