Description

Baumit MC55 W external render is a versatile base coat render used for application on to wood fibre boards.

Baumit MC55 W is an easy to use, natural white, vapour permeable (breathable) lime based contact mortar with multiple uses.

Also use to prepare smooth concrete, mineral and synthetic renders and some painted surfaces to receive a render. 

Use as:

• A base coat for render carriers
• A bonding coat render.
• A reinforcing coat with fibreglass mesh.
• A top coat

Minimum layer thickness: 3 mm (top coat layer); 5 mm (reinforcement layer).

Use when temperatures are above 5 degrees Celsius and protect from strong, drying winds and direct sunlight. 

Baumit MC55 W can be over-coated with Baumit SilikonTop.

Subsurface Pre-treatment

Basecoat renders should be fully cured. Existing mineral and organic based coatings and paints must be sound and well bonded to
the substrate (pull off test and/or cross cut test).

Peeling paint, lime wash, grease stains (from shuttering), other contaminants and film forming layers must be removed. Any cracks are
to be scraped open with a pointed tool to form a “V“ groove. High absorption substrates must be pre-treated with Baumit EasyPrimer.

Friable basecoats are to be pre-treated with a stabiliser such as Baumit MultiPrimer. Algae and mould growth must be removed with
Baumit FungoFluid.

Application

Baumit MC 55 W can be mixed with clean water in a tub to a lump free, smooth consistency with an electric hand mixer. Material which has started setting must not be remixed with water. Mixing with other products (e.g. anti-freeze agents or accelerating agents) is not permitted.

Automated continuous horizontal mixers may also be used. For small areas the contact mortar can be manually applied. For larger areas the freshly mixed mortar can be fed into a mortar pump for spray application. Alternatively, a mortar mixing pump will provide an all-in one mixing and spraying solution.

Preparation of concrete, render and plaster substrates and remediation: Baumit MC 55 W is applied to a thickness of 3 – 5 mm (with embedded Baumit StarTex reinforcing mesh where necessary) and the surface keyed with a brush or plasterer comb.

Reinforcement layer over render coatings and selected render carrier boards: Baumit MC 55 W is applied with a stainless steel notched trowel (10 mm notches). Continuous sheets of Baumit StarTex reinforcing mesh are placed onto the contact mortar, free of creases and with 100 mm overlapping edges. A further 1-2mm of contact mortar is applied “wet on wet “over the embedded reinforcing mesh. Excessive trowelling is to be avoided. Trowel lines are to be removed after hardening.
The overall thickness of the reinforcement layer thickness must be from 6 – 8 mm.

When Baumit MC 55 W is used as a topcoat it must be finished with a suitable water resistant paint.
Protect other materials such as glass, ceramics or metal etc from contamination with appropriate coverings.

Storage

Store in dry conditions and protected on pallets for up to 12 months.