Tile & Stone Installation

Glass Block Mortar

SGM Glass Block Mortar is a special blend of Portland cement, graded aggregates, and proprietary additives formulated specifically for the installation of glass blocks. Computerized batching of raw material ensures a high-quality mortar eliminating the guesswork of job site mixes. Meets ASTM C-279 Type M Mortar.

Product Details



Insure that all framing, pocket recesses, or chassis are in place, clean, and ready to receive glass block. Clean all sides of glass block to permit a good mechanical bond. Consult glass block manufacturer’s literature for placement of anchors, reinforcing, and expansion strips. All panels and sills covered with asphalt emulsion must be cured a minimum of two (2) hours before first mortar bed is placed. Glass block panels shall not be designed to support structural loads. Maximum deflection of structural members shall not exceed L/600.

Provision for expansion and movement joints must be made at jambs and headers of all panels. Do not allow glass block mortar to bridge expansion or movement joints. The design and installation of glass block shall be done using whole units since the cutting of glass block is not recommended.

  • NOTE: Not for use with glass tiles.


The following additional materials may be required to successfully complete the installation of glass block units. Consult glass block unit manufacturer before installation commences.

  • Panel reinforcing.
  • Panel anchors.
  • Expansion strips.
  • Asphalt emulsion.
  • Sealant.
  • Packing (backer rods).
  • Channels (aluminum).


WARNING — EYE IRRITANT CONTAINS PORTLAND CEMENT. Product is alkaline on contact with water. Use paddle for mixing to avoid splashing into eyes or contact with skin. During mixing or application avoid contact with eyes. In case of such contact, flood eyes repeatedly with water and CALL A PHYSICIAN. Wash thoroughly after handling and before smoking or eating. Do not take internally. CONTAINS FREE SILICA — DO NOT BREATHE DUST. Prolonged exposure to dust may cause delayed lung disease (Silicosis). WARNING: This product may expose you to chemicals, including silica, which the State of California recognizes as a cause of cancer. For more information, visit the Proposition 65 Warnings Website (www.P65Warnings.ca.gov). Use NIOSH approved masks at all times to handle silica dust. KEEP OUT OF REACH OF CHILDREN.


Add SGM Glass Block Mortar powder to approximately 1½ galloons (5.7 L) cool, clean potable water per fifty (50) lbs. (22.7Kg) bag. For added water resistance and greater adhesion, the use of Southcrete™ 25 Acrylic mortar Admix in lieu of water is suggested. Machine mixing with a slow speed drill and mixing paddle is preferred (250—350 RPM). Higher speeds are not recommended and will entrain air. Mix the two (2) components together thoroughly until smooth. The proper consistency is obtained when the mortar is applied with the notched trowel to the substrate and the ridges formed do not flow or slump. Allow mortar to slake for five (5) minutes, and then re-mix before use. Do not add any additional water, latex, or powder after the mortar has slaked. Re-mix mortar occasionally during use and discard after initial set in bucket.


Apply a full mortar bed to base or sill; do not furrow mortar. Set lower course of block while maintaining a uniform joint width of ¼ inch (.635 cm) to ? inch (.635 cm) plus or minus ? inch (.3175 cm). Tap blocks into place with rubber mallet to insure a good bond. Steel tools must not be used to tap blocks into place. Use only wooden or rubber tipped tools for tapping glass blocks into place. Do not realign, tap, or move block after initial placement. Install reinforcing panel in the horizontal mortar joints and below all openings with panels. Run reinforcing continuously from end to end of panels. Lap reinforcing not less than siox (6) inches (15.24 cm) whenever necessary to use more than one length. Set succeeding courses of glass block. Spaces at head of panel and jambs must remain free of mortar for caulking with sealant. Strike (rake) joints smooth while mortar is still plastic and before final set. Remove the surplus mortar from face of glass blocks and wipe dry.


Use water to remove uncured mortar. Remove excess mortar from both glass block and tools before mortar hardens. Use of damp clean sponge or soft cloth is recommended.


Minimum cure is reached in 48-72 hours. Curing may vary according to atmospheric conditions.


  • Six (6) Inch (15 cm) Blocks: Forty-five (45) blocks per fifty (50) lbs. (22.7 Kg) bag of glass block mortar.
  • Eight (8) Inch (20 cm) Blocks: Thirty-five (35) blocks per fifty (50) lbs. (22.7 Kg) bag of glass block mortar.
  • Twelve (12) Inch (30 cm) Blocks: Twenty (20) blocks per fifty (50) lbs. (22.7 Kg) bag of glass block mortar.


Up to one (1) year from date of manufacture in unopened properly stored container.

SGM, Inc. warrants this product will perform in accordance with its intended use for a period of one (1) year from the date of manufacture. Any claim for defective product must be submitted in writing to SGM, Inc., and samples of defect must be provided. SGM, Inc.’s sole obligation will be to replace any product determined to be defective by SGM, Inc. EXCEPT AS PROVIDED HEREIN, SGM, INC. MAKES NO OTHER REPRESENTATION OR WARRANTY OF ANY KIND, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR PARTICULAR PURPOSE. IN NO EVENT SHALL SGM, INC. BE LIABLE FOR DAMAGES OF ANY KIND OR NATURE, WHETHER ARISING BY CONTRACT, TORT OR OTHERWISE. SGM, INC.’S SOLE OBLIGATION WILL BE TO REPLACE ANY PRODUCT DETERMINED BY SGM, INC.TO BE DEFECTIVE.