Using roadrunner cull. Starting with a brand new deck, there is a "sweet spot" (measured in time from new deck to this place in the cards wear) where it is very easy to shuttle the card rapidly undercover and over to the right. Then a brief time [passes (a few hours) and the cards become worn in to the point where something about the physical properties of the card have changes and my fingertips are unable to obtain any purchase on the card to be culled and they are sort of running in place and no cards move, so unable to cull the card. I need to figure out what wrong here and how can I change it so the card will move . I am holding the caerds horizontal. Would it be better to have a convexity or concavity and any resource that shows how much of the cards are exposed and wha th left hand is doing in relation to the card to be culled?

Hey Toothlessrufus,

Sounds like typical wear and tear on the deck. The more you practice with cards in each condition the better it will get.
I tend to try and use newer decks where possible and rotate a few of them when practicing. Usually for about 10 minute windows and then on to the next deck. Usually have three on the go for practicing.

Seems to make them last longer and you get more time in that sweet spot with each.

BB.

Toothless,
I appreciate your post. You have hit on something often ignored in card sleights: that many of them only work well with brand new decks. And often many of them don't work consistently even with the best of conditions. So consistency must be the goal of any sleight used. That means that we have to choose only to use sleights that we can adjust to work well all of the time. We may have to change a grip or hold but it should be workable and consistent. If not, then we are in a fantasy world, with "sleights" that only slightly work in only the best of conditions.

I think your problems could be solved by using hand lotion to add tackiness to your finger tips. I have very dry hands and need hand moisturiser regularly. I can underspread cull my weeks-old Bicycle decks as long as the cards don't come in clumps.

This applies to any sleight...practice based on your performing conditions. If you know that you will only perform with brand new decks then practice sleights with only brand new decks. If you are more flexible in what condition of deck you perform with, then you need to have several decks in various conditions and practice your sleights with all of them.

Thanks everyone! I will try all your suggestions. Looks like the friction changes and I cannot get a purchase on the card after too broken in. Reminded me of a physics topic static vs kinetic friction. I guess the coefficient of static friction increases sharply as the cards become worn (The coefficient of static friction is the friction force between two objects when neither of the objects is moving, once an applied force exceeds ti it will move)

Interesting (and frustrating!) how the sleights need to be learned across a wide range of card conditions.

Obviously, there are card sleights which are easier with a reasonably old deck, and others with a new deck. Skin state is of the highest importance too. Sometimes I can do strike bottom deals and at other times, I just can’t deal cards normally from the top !

True, but using any product on your hands can cause the cards to "dirty" on the sides / edges along with premature clumping. Unfortunately, I speak from experience. I use O'Keeffe's Working Hands (once in the morning and at night before bed) and "Chamberlain's Golden Touch" before starting to practice. I use the Golden Touch a couple to a few times a day depending on how many hours and what I am working on.

That said, I practice with brand new to fairly new decks and always perform with a new deck.

You might want to take a look at modifying your practice sessions. Try practicing in 10 to 15 minute chunks -- and spread the sessions out (no pun intended here).

Larry Jennings often recommended practicing a sleight or move for a few times and then duplicating the actions without executing the "special move." His point was that this helps you develop a more natural action.

Daryl used to recommend practicing with cards that have a variety of wear and tear. (switching now and then between decks with different levels of wear.)

Great to hear that excellent advice from Daryl. Makes me miss him again.

But hand lotion can't solve all your problems. I would advise getting all the different techniques on the cull and seeing which one you can use for decks in different stages of wear.
Choosing the right sleight technique is one of the most important tricks in magic that you almost never hear about.