Preserving acrylic paintings

[Carrie Virusso]

Hello,

I recently painted a couple of acrylic portraits and was worried about their longevity. I understand that many people apply a varnish to completed oil paintings in order to prevent some of the effects of aging, but is there something that can be applied to an acrylic painting?

After spending so much time and energy creating these portraits, I would hate to see them dull and crack due to my own negligence.

Thanks so much for any information you can pass on!