Laying and Cleaning Mintaro Slate

Laying Information
Whilst our Company quarries and processes slate into flagstones and many other products, we limit our activities to supply only, thus we have no first hand experience of installation which in every case has been carried out by those to whom we supply.

So, as a general indication only, we provide the following:-

Bedding is normally on silica sand or crushed rock, washed if necessary to remove clay or other solubles. We've been advised that crushed dolomite should be avoided in case subsequent breakdown releases harmful salts.

As a sedimentary rock the surface of slate is minimally porous, when cement or adhesive are used for bedding, or when grouting joints, spilt material or liquid should be sponged off progressively before having the opportunity to set, which could mark the surface.

On Compacted Sand or Fill
In courtyards, verandahs and light traffic areas, slabs are sometimes set on levelled sand. AdelaideBrighton Cement has advised that a small addition of dry cement (1:12) can adequately stabilize the bed for higher loading.

On Cement Treated Rubble
We're aware of footpath slabs being set on stone from Adelaide based quarries crushed to gravel and smaller, mixed with 4% by weight cement and set over rolled fill. In some cases sourcing the correct rubble has seen extensive analytical testing for compression, strength, flexibility and elasticity.

On a Base Slab
Within buildings having a base concrete slab, slate may be set on a mortar bed of 3 or 4 to 1 sand to cement, allowing a thickness of say nominal 25mm under the slate to allow working. In some cases an adhesive additive (e.g Cemstick, Abacrete, Lockcrete) is mixed say 1 to 10 into the water, although not all layers to whom we have spoken think this necessary.

The above recommendations are made in good faith and serve only as a GUIDE. We accept NO RESPONSIBILITY whatsoever for any occurrences arising out of the use of the above suggestions.

Cleaning of Slate - Domestic Applications
To assist with the inconvenience of spillage or the spoiling of our natural products appearance we offer the following suggestions:-

  1. Try water (soak if necessary). Scrub with a kitchen scourer pad or nylon brush, may be dry 0000 steel wool localised to the concerned area
    If "NO-GO" The problem may respond to water based cleaners:-
    e.g. - Detergent (biodegradable)
    • Amway
    • Handy Andy
    • Other ammonia type cleaners (1/2 cup ammonia to a gallon of water)

  2. Always limit the cleaning to the immediate area if possible and thoroughly rinse with water. Frequent overuse of ammonia solution may eventually dull the stone surface.
  3. IF IT LOOKS LIKE OIL, or it doesn't respond to water based cleansers try hydrocarbon types such as:-
    • Toluene
    • Acetone
    • White Spirits

  4. These you may need to leave on as a puddle for the stain to dissolve back into the solvents. Swab off with a cloth. Turps or kerosene may work but probably will leave a wet looking mark, taking sometime days - weeks to evaporate out.
  5. INK STAINS (pen, ink, crayon) - try with lacquer thinner or acetone, bleach or hydrogen peroxide.
  6. PAINT STAINS - small amounts can be removed with lacquer thinner or scraped off carefully with a razor blade. Heavy paint coverage should be removed with a commercial liquid paint stripper. DO NOT USE ACIDS OR FLAME TOOLS TO STRIP PAINT FROM STONE.
  7. BIOLOGICAL STAINS (algae, mildew, moss, fungi) - clean with a diluted (1/2 cup in a gallon of water) ammonia, bleach, or hydrogen peroxide. WARNING; DO NOT MIX BLEACH AND AMMONIA! THIS COMBINATION CREATES A TOXIC GAS!
  8. Soap scummed areas try sprinkling Epsom Salts, and then wring out a cloth in a solution of one part bleach to four parts water and rub the floor with it. Rinse the floor with cold water and leave to dry before walking on it.
  9. For salty-looking water marks on slate, rub with vinegar and wipe off.
  10. RUST STAINS are difficult to shift. Oxalic Acid (which is a poison) may work.
  11. SLATE SEALERS generally can be removed by the suppliers products, if not try a paint remover then water to neutralize.
  12. Cement, mortar should be cleaned off as it comes in contact with the stone with a sponge and a lot of water. Commercial brick cleaner. (i.e. diluted hydrochloric acid) can be used but a neutralizer and copious amounts of fresh water should be incorporated to remove any traces of the brick cleaner.

Remember always wear the appropriate personal protection when handling cleansers in a fully ventilated area.

Please remember that you should always limit the cleaning of an area to the smallest area necessary.

The above recommendations are made in good faith and serve only as a GUIDE. We accept NO RESPONSIBLITY whatsoever for any occurrences arising out of the use of the above suggestions and if you decide to implement them you do so entirely at your own risk.