My oil pastels won't blend very well. What to do?

I am doing an oil pastel mural. My pastels won't seem to blend very well. i'm using the short, fattish kind. not the long skinny pastel pencils. so anyway, i like how putting white over two colors makes it blend well, but i just ran out of white. I'm a beginner at using pastels. Blending with paper towel isn't working too good. Should i put water on the pastels? What should I do?