ISOSET Firebrick Mortar

The Isoset Brick Mortar, a thin-set masonry adhesive, can be used in either interiors or exteriors for laying of firebrick. It is the specified firebrick mortar to be used in all Isokern Fireplaces. The Isoset is available in 50lb buckets, approximately 50 lbs of prepared mortar will lay up one hundred and fifty 9 x 4½ x 2½” Straights.



Dry, hydraulically setting, non-water soluble, medium duty 2700°F mortar.


Add .75 quarts of water per 10lbs of dry product until completely blended.

Only mix what can be utilized within 15 minutes

Do not retemper (the addition of water after the chemical reaction has begun).

The use of warm water will accelerate setup

Joint thickness should be thin (1/4”- 3/8”) for firebrick

Complete set time is between 48 & 72 hours.

For best results, please allow seven days before heat is applied.

Approximately 35 to 40 lbs of prepared mortar will lay up one hundred 9 x 4½ x 2½” Straights.

DO NOT add additives such as fireclay, sand, cement, or other accelerators.


May cause cancer if inhaled. Causes skin irritation. May cause respiratory irritation. Causes serious eye irritation. May cause damage to organs. – Lungs Wash thoroughly after handling. Do not eat, drink or smoke when using this product. Use only outdoors or in a well-ventilated area. Wear protective gloves / protective clothing / eye protection / face protection. In case of in-adequate ventilation wear respiratory protection. IF INHALED: If breathing is difficult, remove victim to fresh air and keep at rest in a position comfortable for breathing. IF IN EYES: Rinse cautiously with water for several minutes. Re-move contact lenses, if present and easy to do. Continue rinsing. IF ON SKIN: Wash with plenty of soap and water. Store in a closed container. Keep cool.

We have owned an Isokern Fireplace in our home for over 9 years now. We like the Isokern pre-engineered firebox produces a consistent fire draw. In the past we had experienced some poor draws in our existing fireplaces and wanted a better fire experience. We also liked that the interior firebrick could be customized to give you various looks for the fireplace. We would definitely consider another Isokern Fireplace for our outside porch.

Barbara and Bob Dougherty

We have been working with Earthcore for many years. On the product end, the Isokern Masonry products they manufacture are second to none. The precision in which they build their components is unlike anything we have ever tried.

On the business end, we love the staff at Earthcore! From the employees I met at their factory, to the owner of the company I had the pleasure of meeting at a trade show in Nashville, TN……this company is a great organization that I look forward to growing with for many years to come.

Hill Dickerson
Dickerson Hearth Products

I’ve been woking with Earthcore for years. Claudia has been very helpful making things go smoothly out in the field and in helping with choosing the right fireplace to achieve the best looks. I have had great feedback from past customers on the product and plan on continuing to use these fireplace units.

Bruce Winfrey
Winfrey Design Build

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