The problem with Irish Spring is that it covers up the odor; it does not get rid of it. Things like charcoal and cat litter (it may depend on the type of cat litter!) actually absorb odors. However, if the varnish is still out-gassing, you will probably need to add a layer to the varnish. I am thinking of a coat of polyurethane. You would have to test on a small spot, as whether the polyurethane will stick or not depends on the type of varnish used. I have an old featherweight case that had a moldy smell no matter what I did. Finally found that leaving a Dr. Scholl's shoe insert containing charcoal was enough to absorb the odors. I don't think that would be enough to protect your quilts, though.