I have an entire room where the ceiling is poly treated pine wood, gold stain. I would like to whitewash this and lighten it up in there. Is there a product or way to stain it white without stripping the poly off first?
The challenge will be getting it to stick since it is probably oil-based poly. You will need to sand or otherwise degloss the surface that is there. Then, you might try making a glaze with the density you want using poly and white. You should stick with oil for this I think if that is what is already on there.
White washing is usually done before polyurethaning, its a mixture of a color of paint of your choice, mixed with 25% water per gallon of paint, and flowtrol, then its brushed, rolled on, letting it sit for a couple of minutes, then ragging it off in one direction. You can also apply a base coat first of your color choice then apply another color over that using the whitewashing method. That will give you two different color. Then you would normally apply your polyurethane, because the pine is already polyed, its sealed and will not accept any paint, but if you wanted too you could sand it, scuffing it up, clean the surface, apply a bonding primer, then apply a top coat of paint, or you could use minwax polyshades which already has poly in it, polyshades will go over the existing poly, but I would still sand first and clean the surface.