How can you tell if the exterior stain is oil or acrylic? Unable to get oil due to going green. Can an acrylic stain be applied over an oil stain? If not what must be done in order to use an acrylic over oil?
For exterior stains, yes an acrylic may be applied over an alkyd. This is possible for many reasons.
1) Generally the coating has aged enough to allow adhesion of the acrylic.
2) Exterior coatings have much more acrylics in them for durability purposes. The side benefit of this is added adhesion.
3) Exterior alkyd stains do not have the glossy film build which is the major factor in lack of adhesion between acrylics and alkyds.