My first question would be how old is the varnish? My 2nd would be what color was the leather you put it on? It may have absorbed some color from that.

Before good fabric paints came along I would mix my multi-purpose varnish into my paint to eliminate the need to varnish afterwards. Multi-Purpose Sealers are adhesive and durable and they seal most hard craft surfaces for indoor or outdoor use. They can even be mixed with paints to eliminate the need to varnish outdoor surfaces.

I have used Flecto Varathane Diamond Satin finish for many years with great success (now owned and sold by Rustoleum).

http://rustoleum.com/CBGProduct.asp?pid=70

More info.....

http://www.polyclay.com/varathane.htm

These days I prefer to use a paint that's made for the surface so I don't have to deal with a finish. I absolutely love Tulip's So-Soft Fabric paint. It air cures and you don't need to seal or heat set it.

Thank you for your insight. The varnish is new. I got to thinking and I think my brush may have gotten mixed up with one I had used with paint. That would explain why this hasn't occured before. I think I will try mixing the varnish with the paint like you mentioned. Thanks again!

I am curious to know what you are painting. :-)