Bumper Number Material

I’ve been told that some teams use slicker bumper cloth to assist in escaping pins, but doesn’t the bumper number material also change the coefficient of friction of the bumper? What is the best bumper number material/method to complement slicker bumpers?
On the other hand, what is the best bumper number material/method to complement rougher bumpers?

To start, one of our mentors speculated that sewn on numbers might be rougher because of the seams.

In the past my team has always painted on the letters with a stencil. They stayed on their I believe but it didn’t look good. This year we are going to try to use HTV (Heat Transfer Vinyl), but the only problem is that there is a very thin margin of applying the vinyl, and melting the slick bumper material.

Paint would probably be the slickest because it will leave a bit of the fabric still exposed. Vinyl has differing levels of friction on the surface. Some of the stretch vinyls for athletic jerseys are really rubbery and sticky, while the standard vinyls are all pretty slick. Cold peel vinyls are typically thinner and slicker than hot peel vinyls.

As to the melting of the fabric, use a heat press. Someone in your area has one. They have a temperature control that is the reason why they cost so much. My classroom press will stay within 5 degrees of the set temperature and the reported temperature is within one degree of actual. You can find the minimum temp to apply vinyl and the maximum temp the fabric can handle andsettle on somewhere in the middle.