Mortar Bed Setting
1. The slab should be clean and
free of all debris. If any curing compounds were used, scarifying
may be necessary.
2. Wet down or dampen the slab,
however do not allow standing water or puddling.
3. Spread a bed of approximately
3/4" thickness mortar mix consisting of 1 part Portland cement
and 3 parts mason's sand (1:3 mix).
4. Tamp slate firmly into setting
bed until the desired level and uniform plane are met.
5. Remove any excess mortar.
6. Carefully lift slate and butter
the back with a paste of neat Portland cement.
7. Tamp slate back into place.
8. Joints (3/8" minimum joint
is recommended) should be filled and pointed with a 1:2 grout mixture,
preferably on the same day of installation.
1. The slab should be clean, free
of all debris and smooth finished. A variation in level should not
exceed 1/8" in ten feet.
2. Apply dry-set Portland cement
mortar or latex-Portland cement mortar with a trowel over an area
of which slate can be applied while mortar remains plastic.
3. With a notched trowel, comb
mortar to an even setting bed, being careful not to scrape mortar
from slab. Bed thickness should be approximately 1/8" with
no bare spots.
4. Slate should be placed with
a slight twisting motion and tamped level to finished grade and
uniform plane. (A minimum contact of 80% is required. Larger pieces
should be "back buttered" to obtain maximum possible bond.
In wet areas, a 100 % contact bond is required.)
5. Care should be taken to achieve
joint allowance with a minimum amount of adjustment.
6. Joints should be grouted with
the specified grout after setting bed is dry.
1. The slab, sub-floor or existing
floor should be clean and free of all debris. Existing sub- floor
should be solid and free of any loose material. Painted or otherwise
treated surfaces should be sanded with coarse sand paper.
2. With a "vee"-notched
trowel, spread the specified mastic being sure not to leave any
bare spots. Spread only an area that can be comfortably reached
to install the slate.
3. Slate should be pressed firmly
into the mastic, but not tamped. Joint allowance should be obtained
with as little disturbance as possible.
4. Allow mastic a minimum of 24
hours drying time before grouting joints.
5. Grout joints with a latex grout
or as specified, sponging the slate frequently to remove excess
Interior flooring is usually supplied 1/4", 3/8", &
1/2" thickness with cleft face and the bottom gauged to allow
thin-setting. The larger the sizes of slate tile, the more critical
the level of the slab or sub-floor becomes.
Slate should be periodically sponged down during installation
to prevent mortar stains from forming. Water should be kept clear
and clean by changing often. After slate has been set for at least
14 days, it should be scrubbed with an approved detergent, followed
by a thorough rinsing with clean water. After rinsing, slate should
be wiped with soft toweling or a chamois. Tough mortar stains that
have set can be removed with muriatic acid and water (1 part acid,
10 parts water), however, care should be taken as the grouted joints
are vulnerable to the acid.
Treatments - Although the slate needs no sealer or other
treatment, the joints are susceptible to minor cracks and separations.
Use of a sealer / impregnator is useful in protecting water infiltration
through these cracks into the setting bed. Sealers usually
darken the slate and give a glossy appearance. Natural cleft finish
and Sand Rubbed finish may be sealed suitably, however, sealers
may not adhere nor give a desirable appearance to Machine gauged
or Honed finish. Impregnators usually do not as radically
alter the color of the slate and give a more satin finish. As with
sealers, Machine gauged and Honed finish may not accept the application
of an impregnator. NOTE: Care should be taken in selecting
a treatment that is slip resistant.