Use plaster and masonry mortar for plastering

Especially due to the modern architecture in industrial chic formerly only functional masonry mortar have made their way to plaster. Rough surfaces in concrete look, rough spray plaster and intentional industrial design can be produced well with the plastering of plaster and masonry mortar. There are some things to consider when choosing materials.

Mortar can be used as plaster and plaster as mortar

A fundamental difference between mortar and plaster is the type of application and the order strength. In most cases, related material mixtures meet, which only differ by processing. Both plasters and mortar can be dyed, structured and finished.

In order for plaster surfaces to adhere well and permanently to mortar substrates, similar physical properties are important. In rooms, humidity and temperature change. If the mortars and plasters involved react very differently, damage is inevitable. This challenge already applies to the overfilling of joints. The top mortar, which can also be referred to as plaster, should possess the properties of the load-bearing sub-mortar.

Soft on hard

A basic technical rule for professional plastering is that covering layers must always be softer than the substrate. Lime mortar is softer than cement mortar and should therefore only be covered with lime plaster or other softer plasters.

In the case of plaster and mortar mixtures, the mixing ratio of mortar or plaster determines the hardness. If plastering work is done by yourself, the "soft" parts such as hydrated lime or gypsum should be increased. On premixed ready-to-use packs, manufacturers note the hardness or compressive strength of the product.

Combine similar mortar and plaster types

The saying "Equal and like to join" is true when plastering with and from plaster and masonry mortar, while "opposites attract" rather lead to damage risks.

Waterproof resin plasters are not suitable on a mortar substrate. The closer the connection between plaster and mortar fails, the more closely related should the mixtures be. When repairing cracks, the lion's share of the same binders should meet.

Tips & Tricks

If you choose between a plaster and a mortar, only the aggregates determine the difference. In general, mortars used as plasters are more difficult to process than vice versa.

Product Image: Zaharia Bogdan Rares / Shutterstock

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