ᐅ Plastering of window reveals (also known as window jambs)

Hello

I would like to plaster several window reveals. A picture is attached. The plaster will not be visible later (wooden facade). The main goal is to create a clean surface for the window.

I would like to apply the plaster myself. A trial mix with 3 parts limestone cement and 14 parts washed sand produced moderate results. Unfortunately, I do not know the exact proportion of lime in the cement.

According to an expert, the original plaster is a cement-based plaster that contains lime for better workability. However, I have not found any clear recommendations for what is best in my situation. Should I use lime or hydrated lime? How much cement? How much sand?

Substrate: Mostly red brick. Occasionally concrete (old window sills).
Is a bonding agent needed for the concrete?

Could someone help me?
Thank you very much in advance

Michael

I believe the masons here simply used mortar. It probably isn’t necessary anymore anyway.

I don't know the exact mix, but use hydraulic lime plaster. It's best to get it in bags, since you won't need that much.
Yes, you can also use masonry and plaster mortar. However, you must have the exact mix for that and also be confident in applying the plaster yourself. I tried once and failed miserably.