Installation of flooring using the dusting or barbotine (slurry) technique

At times, in order to expedite the installation of flooring, the technique of dusting cement over a bed of fresh mortar and then covering with the piece is used. However, this technique is insufficient due to the technological evolution of the ceramic tiles towards other types of pieces without absorption and large formats.

Preliminary analysis

The adherence of ceramic tiles or stone material with medium-to-low absorption is null with this type of application by dusting cement over a layer of fresh mortar, due to the fact that:

  • There is no chemical adherence and the cement only provides physical adherence on penetrating the filaments in the porosity of the piece.
  • Cement open time is null, as the cement is not adhesive, producing fast anti-adherent drying of the floor surface.
  • We find that large formats do not adequately impregnate these types of substrates.


For all these reasons, we will need an adhesive:

  • With extended open time, to avoid possible drying to a larger extent.
  • With redispersable resins, to ensure adherence to tiles without absorption.
  • Very fine, to improve homogenization by dusting.
  • With high resistance, to support the quantity of water used in the barbotine (slurry) technique.

Technical considerations

  • GECOL Espolvoreo is always applied over a bed of fresh mortar, preferably GECOL Sec silíceo of the GM – 7.5 type or GECOL Hormigón seco.
  • When installing the flooring, attention must be paid to the cement dose rate and to the selection of the particle size of the aggregates in order to minimize hygrometric retractions.
  • As a rule, the screed must be compacted and screeded and must be perfectly flat and suitable for the application of the covering material.
  • It is essential for the substrate to be sufficiently hydrated.
  • It is very important to not use it in floors for application once the setting process has begun and when they are subject to continuous rising damp.
  • For exterior floors, the substrate must have a slope equal to or greater than 1% to allow for water drainage.
  • When applying the tiles, it is important for you to press down firmly on them so that they are all fully embedded in the adhesive with no empty spaces between the tile and the substrate
  • GECOL Espolvoreo is a product which, by nature, is prone to forming an anti-adhesive film, due to which it is advisable to apply it in a small working area (approximately 10 m).


  • Dusting technique:

(Pieces up to 1,000 cm2)

  • Apply and distribute a layer of at least 2 mm over the fresh mortar bed uniformly.
  • Moisten with a sprayer with sufficient water and trowel to better ensure that everything is correct before applying the ceramic tiles.
  • Tap with a rubber mallet crosswise to the application, constantly checking the adhesion of the tile.
  • Hydrate even after the application of the tiles.


  • Paste or barbotine (slurry) technique:
  • Mix the product with clean water until obtaining a smooth and lump-free paste.
  • Let settle and remix the paste.
  • The amount of water indicated on the packaging is a guideline and may vary by a small percentage depending on the geographic region where production takes place.
  • Mixes with more or less thixotropic consistency may be obtained, depending on the application desired.
  • Adding excess water can cause the thickness to be reduced due to shrinkage during the plastic phase of drying, reducing its ultimate performance, as well as result in a poorer application of the adhesive.
  • Apply GECOL Espolvoreo on the substrate and screed the thickness with a notched trowel.


For formats larger than 1,000 cm2 apply a thicker slurry and use the buttering technique.

  • Align the tiles with the use of spacers.
  • Check that the tile does not have any dust, dirt or poorly attached layers.
  • It is not necessary to wet the tile before placing it. Only if the back of the tile is very dusty do we recommend washing it with clean water.
  • Apply the tile and tap it with a rubber mallet until the mark or groove left by the notched trowel is broken, periodically checking the stickiness of the pasta (lifting up the tile already installed).
  • The adhesive should be checked regularly to ensure there is no skinning of the adhesive and that it is fresh.

Otherwise, it should be re-combed with a toothed trowel, but never wet the adhesive.

A second consideration to be considered is the design of the joints, respecting:

  • 3 mm joint spacing between tiles.
  • Perimeter movement joints in corners and changes in plane, height or material.
  • Movement joints that constitute maximum surface areas of 50 m2 indoors, 25 m2 outdoors and 16 m2 with dark colors on exterior surfaces.
  • Expansion joints between door and structural cavities of the building.

All expansion joints should be filled with elastic mastics such as GECOL Elastic-MS.

Jointing mortar must be applied at least 7 to 10 days after installing the flooring. In this way we will ensure that substrate does not have residual humidity.

Commissioning will take place at least 48 hours after executing the joint.

Recommended products


Joint mortars

From 0 to 20 mm quick setting

Up to 6 mm

From 3 to 15 mm

Flexible mastic



Masonry mortar

Dry concrete H-25

Warnings: The data provided by this Constructive Solution were prepared based on standard onsite installation processes. However, we recommend that you consult our Technical Department in the event of any specific circumstance