Natural shellac is a widely used finish for new work and restoration. It is an excellent sealer for use on woods with high resin content (e.g., pine) to prevent bleed-through after painting.
Ours is de-waxed and comes in flake form for easy dissolving. It is available in light yellow, amber and dark auburn in 1/4 lb (113g) and 1 lb (454g) packages.
Shellac should be dissolved in denatured alcohol.