RJ2.09   LIME PUTTY RENDERS

PRODUCT DATA SHEET

DESCRIPTION:

Lime putty based external renders are manufactured from 6 month mature Chalk lime putty and particular sands in the proportions of 1:2 to 2½. It is often appropriate to gauge (on site) with a pozzolanic material such as Metastar 501 (RJ 7.04) at c.10% by volume to mortar.

USES:

For all coats of external render. Horse hair is added to basecoat(s) at 2½kg/ tonne. The basecoat(s) are applied maximum 10mm thick and top-coat c.8mm.
The top-coat is normally trowel-applied and finished with a wood or sponge float, but it can be thrown on as roughcast or harling. Lime putty renders must be finished with casein bound limewash (RJ 3.02).

AVAILABILITY:

SHELF LIFE:

Horse hair deteriorates in a wet lime mortar. Use haired base-coat renders within one month of purchase. Lime putty renders will stiffen in the bag over time but can be readily plasticised by thorough re-mixing without the addition of water. The mortar will begin to set once a pozzolan is added. Do not remix pozzolan gauged mortar.

Protect from frost.

PACKAGES:

COVERAGE:

HEALTH & SAFETY

OBSERVATIONS:

Tradesmen familiar with the use of lime putty renders, and with experience of their successful use should be employed. Lime putty renders do not perform as modern cement or hydraulic lime based materials. Although there is a lime: silica reaction when a pozzolan is added, the primary setting mechanism is the reaction with atmospheric Carbon dioxide in the presence of moisture. This 'carbonation' is slow, and control of the drying and curing process by 'tending' and protecting is crucial to success and long term performance.
Do not use in temperatures of 5 ºC and falling. Protect from frost.

See TAN 7 - Internal Plain Lime Plastering.