We have restained our table and have put the first coat of Helmsman on it and I have lightly sanded to get ready for the second coat.However, we dipped one of the staining pads into the can and the varnish and the stain have now mixed. I have tried to filter the varnish but it is now the stained color. Is the rest of the varnish still good to use or will it cause bubbles, etc.?
If both the varnish and the stain are in the same solvent, then mixing should be fine. (The labels will specify either water or mineral spirits cleanup.)
Don't be tempted to not stir the varnish before use, as there can be flatting agents that collect in the bottom.