Stained Douglas Fir Door . This will help you to get a really even stain since having a lot of excess can definitely worsen the natural splotchy pattern of douglas fir. Woods like fir and pine often need a preconditioner to even out stain color. Exterior Douglas Fir Prarie Doors with Sidelights from www.nicksbuilding.com Douglas fir is also prone to blotch so a wood conditioner should be used prior to staining. Wood stains on planed s4s and rough sawn douglas fir with minwax and benjamin moore arborcoat. Best stain for douglas fir door reviews.