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Plastering with a Spraygun – Guide

This method is particularly suitable to ensure optimum bonding even on smooth surfaces. Spraying is recognized as the best method of application allowing sharper sands and lower water content in the mortar mix. The speed of work is considerably increased and an average of 1000 square feet per day per man is quite normal. The pressurized application also allows to build up the thickness of a layer to 1″. The pressure should not exceed 3.5 Bar*. Two coat work is normally sufficient with the use of a spray gun.
Overall render thickness
3/4″-1″1″-1 3/8″up to 1 9/16″
On surfaces with low keying (for thickness above 1 9/16″
please consult us.)
Stipple coat
NHL 5 or NHL 3.5 @ 1: 1.5
Sands: well graded 5mm down to 0.075
1/8″- 3/16″1/8″-3/8″3/16″-5/16″
Leave 24/48 hours as sprayed to provide good key
1st coat
NHL 3.5 @ 1:2 or NHL 5 @ 1:2.5
Sands: well graded 3mm down to 0.075
3/8″- 5/8″3/8″-5/8″3/4″-1″
Leave for a minimum of 4 days depending on weather conditions, coat thickness and the plasterer’s judgment.
Level using a straight edge and key with criss-cross pattern.
If this is also the finishing coat (3/4″-1″), depending on the finish required, a finer sand can be used (#6 to #200 mesh).
2nd coat (finishing coat)3/16″-5/16″3/16″- 3/8″3/16″-3/8″
NHL 3.5 @ 1: 2.5 or NHL 2 @ 1:2
Sands: #6 mesh down
Finer sands for wooden float or smooth finishes (#8 or finer) can be used. In these cases the thickness should not be over 3/16″.
Notes: background preparation as per good practice. Always dampen surface before each application. On high suction background ensure that this is thoroughly dampened (no standing water on surface), if necessary several times, to minimise shrinkage. Cure work for few days with water mist. Protect against rain, frost, drying wind and direct sun for 2 to 7 days. If dubbing out is required the mortar ratio should be the same as the 1st coat. Leave dubbed out areas as sprayed to provide a key.*Sablon S3 Hopper gun

Overall render thickness
3/4″- 1″**1″-1 3/8″up to 1 9/16″
On well keyed surfaces.
(raking joints not necessary)
(for thickness above 1 9/16″
please consult us.)
1st coat
3/8″-5/8″
3/8″- 5/8″
NHL 5 or NHL 3.5 @ 1: 1.5
Sands: well graded #4 down to #200 mesh
Trowel off high spots and leave 3-4 days as sprayed
to provide good key.
2nd coat 3/16″- 5/8″3/8″- 5/8″3/8″- 5/8″
NHL 5 @ 1:2.5 or NHL 3.5 @ 1:2
Sands: well graded #6 mesh down to #200
This can be the finishing coat for a 3/4″- 1″ render. If a smooth finish is required apply a 3rd coat as below. Level using a straight edge and key with criss-cross patterns.
Leave about 7 days depending on weather conditions
and the plasterer’s judgment.
3rd coat (finishing)1/8″- 3/16
Smooth finishes only
otherwise use 2nd coat
as finishing coat.
3/16″- 5/16″3/16″- 5/8″
NHL 3.5 @ 1: 2.5 or NHL 2 @ 1:2
Sands: depending on the finish required.
Finer sands for wooden float or smooth finishes (#8 or finer) can be used. In these cases the thickness should not be over 3/16″.
** This thickness can be achieved in one coat
(several passes) with suitable aggregates. Please consult us.
Notes: background preparation as per good practice. Always dampen surface before each application. On high suction background ensure that this is thoroughly dampened (no standing water), if necessary several times, to minimize shrinkage. Cure work for few days with water mist. Protect against rain, frost, drying wind and direct sun for 2 to 7 days. If dubbing out is required the mortar ratio should be the same as the 1st coat. Leave dubbed out areas as sprayed to provide a key.

 

The information provided in these pages is of general nature only and does not constitute a full specification.

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