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Technical Data Sheet (TDS)

M420 Spot-Tack

Universal Mounting Adhesive

Special features

  • Install almost anything over anything
  • One substrate has to be absorbent
  • Unmatched holding power - installs bricks to the ceiling

Product Description
Spot-Tack is a Universal adhesive used to connect multiple products to multiple surfaces instantly. It is designed specifically for affixing products in either vertical or overhead configurations. It has an immediate grab which makes it ideal for tile, pavers, tumbled marble, and many other types of flooring and decorative products. As long as one of the two products is porous, the types of products to adhere to are limitless.
Pre-Installation Checklist
A successful installation requires proper preparation of the subfloor. Read and understand all applicable guidelines and technical data sheets before installation. Follow industry standards and flooring manufacturers' recommendations for subfloor moisture content, design, layout, and application of flooring materials. All flooring material's backing must be solid, sound, and free of anti-adherents. All slab constructions must meet the specific requirements of the floor covering to be installed.
Sub Floor Examination
Prior to installation, the subfloor must be checked according to applicable installation guidelines. It must be solid and sound, flat, permanently dry, clean, free of chaps, indentations, and anti-adherents, as well as resistant to pressure and tension. The moisture content of all floors must be measured before installation.
Moisture content in concrete subfloors must be below 3#/24hr/1,000SF using the Calcium Chloride Test or below 75% RH using an in-situ probe per ASTM F1869 and F2170.
Sub Floor Preparation
The condition of the subfloor will determine which type of mechanical treatment is required (e.g. wire brushing, sanding, grinding, or shot blasting). Dust, paint, curing compounds, sealers, residual adhesives, or other surface contaminants MUST be removed and a porous surface achieved by suitable means. The extent of subfloor preparation can only be determined at the site by the installer. Clean the surface with an industrial vacuum cleaner and tack the floor with a damp microfiber mop before application. Do not use sweeping compounds unless they are water-based as most others will contain oil or wax which will act as an anti-adherent and prevent primers, sealers, leveling compounds, coatings, and/or adhesives from bonding to the concrete. Cracks and gaps must be treated prior to application of primers, sealers, leveling compounds, coatings, and/or adhesives (for details see Technical Information #19 @
Store and transport protected from freezing. Recommended minimum temperatures are 35°F for transport and 40°F for storage. Do not stir the product if frozen, allow it to thaw completely.
When using other than STAUF products in conjunction with STAUF primers, sealers, leveling compounds, or adhesives, STAUF denies any and all responsibility for any ensuing problems and/or damages without prior written authorization from STAUF.
This adhesive is mold and mildew-resistant and water resistant when fully cured. However, it will not prevent moisture-related damages to wood flooring unless it is used as a moisture barrier (if applicable) within the limitations set forth in the Technical Data Sheet.
In case of an accident, injury, spill, or exposure, see SDS for information. Consult the Technical Data Sheet at for updated information.
The foregoing representations are based on the results of our most current product and material testing within a controlled environment and are of a non-obligatory advisory nature only. As such, they do not constitute an express or implied warranty of any kind including the Warranty of Merchantability and/or Fitness for a Particular Purpose. Because we have no control over the actual quality of workmanship, materials used, and worksite conditions, STAUF USA LLC will in no event be liable for any incidental and/or consequential damages. Therefore, we strongly recommend that prior on-site testing be conducted to refer to and study the suitability of the product for the intended purpose. With the release of this Technical Information Sheet, all its prior versions become invalid. For warranty and warranty disclaimer information please see our Limited Lifetime Warranty @
General Features
  • LEED qualified
  • Contains no isocyanates
  • Dries in less than 2 hours
  • High shear strength
  • Contains no solvents
  • Contains no VOC (calc. per CA Rule 1168)
  • Nonflammable
  • High solids content
  • Ozone friendly
  • Dispersion base cleans with water
  • Not freeze/thaw stable
Installation Features
  • Grabs quicker, less slippage
  • Wet lay - no flash time required
  • Superior green grab
  • Non-slump formula
  • Bridges normal sub floor variations
  • Very low odor
  • Cleans with warm water and soap
  • Higher temp will shorten drying time
  • No risk of sensitization
Long Term Features
  • Resistant against aging
  • Eliminates hollow spots
Approved Materials
  • Engineered Wood Flooring
  • Ceramic & Stone
  • Wall coverings
  • Wall/Cove base
  • Planks, up to 7 in wide
Approved Substrates
  • Concrete Slabs
  • OSB (underlayment grade)
  • Plywood (underlayment grade)
  • Drywall
  • Plaster
Approved Primers
  • Primer is normally not required
Approved Sealers
  • Sealer is normally not required
Approved Leveling Compounds
  • Leveling is normally not required
Approved Trowels and Spread Rate
  • Cove Base: up to 300 LF/gal
  • Wall panels: up to 40 SF/gal
  • Ceramic Tiles: up to 30 SF/gal
  • Stone/Brick: up to 20 SF/gal
Cure Time until Normal Traffic
  • Between 24 and 48 hours
  • Use soap and water
Temperature Range during Installation
  • 50-90F (10-32C)
Relative Humidity Range during Installation
  • 30% - 80%
Packaging Size
  • 3/4 gal. Plastic Pail
  • 4 count Case
  • White
pH value of concrete
  • Must be below 12.4
  • Above 32F, not freeze/thaw stable
Shelf Life
  • 24 Months in original, unopened container
Open Time30% R/H50% R/H80% R/H
50�F/10�C15 min. 20 min 25 min 
70�F/21�C10 min 15 min. 20 min 
90�F/32�C5 min 10 min 15 min. 
Revision: 2022-04-18 14:05:43

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