Milk Paint is durable enough to stand up to low or medium wear without top coat. If increased sheen or maximum durability for high use areas (cabinets, table tops) is required, GF recommends applying 2-3 coats of GF's High Performance or Enduro top coats after the Milk Paint is dry [1-2 hours].
GF's stance: Topcoat will provide greater durability and protection than wax finishes over time. While wax finishes are lovely, they typically show wear (ex: fingerprints) and require semi-annual to annual maintenance. Furthermore, nothing adheres well to wax, which can impact future finish changes. Even though there is internet chatter about removing wax with 3rd party products or mineral spirits, the risk of a failure in re-coating over a wax finish is very high.
GF's Milk Paints are an excellent finish for outdoor projects without top coat.
Oil based top coat can be applied over Milk Paint so long as 24 hours wait time is allowed between the two products. When moving from a water based product to an oil based product it is essential that the first is dry before applying the second.