Refractometer question

Ok so I've got a few brews under my belt and my product is getting better. But I hate taking large samples of my beer or wort to float a hydrometer and I needed a little better control of my process so I got a compensated refractometer. My question is, when taking multiple samples how do you clean the prisim between samples? I have been rinsing and drying with a soft paper towel, or sometimes just wiping off with a paper towel to get a new reading of the same or different wort. Is that the way to do it? I can't think of a better way, I was hoping maybe somebody had a really clever method.

I would say a clean damp soft paper towel.

I just use whatever wet rag I have laying around. As long as it isn't caked with dirt or anything abrasive it will be fine.