There are a few different things that may help prevent the gymnast from ripping too easily. Most are just preventive measure to keep their hands from being too soft.
1. No lotion or softeners for the hands
2. This is one the kids like. Don't do the dishes. If they must do dishes (my kids do) wear gloves to keep the hands from soaking so long.
3. Avoid long baths or showers.
I'm sure there are a lot more things that soften the skin we could add but these were just a few examples.
I have noticed that some kids rip often (once a week) some kids never rip. My daughter did giants with no
grips, no chalk and water on her hand and never ripped. Other kids wear
grips, tape under the grips and still manage to grip.
One other contributing factor is what I like to call the "Grip O' Death". This is the term I use when the kids hang on to the bar as if they would die if they let go. We would like for them to hold on just tight enough. I use the old .38 Special song "Hold on Loosely" but don't let go as my example in those cases. Basically, the tighter you hang on, the more friction there is between the hands and the bars.
Other things that enter into the equation are the skills they are doing as well as each time they work a new skill, they are more likely to go back to the death grip on the bar.