(773) 588-0800

Lime Mortar Supplier

Henry Frerk Sons is pleased to offer a full range of masonry restoration products, including:


  • The nation's broadest selection of historic lime mortars
  • Stone, brick, and terra cotta repair mortar, and we stock the 17 most common colors used in the Chicago area
  • Mineral coatings and stains for historic terra cotta, stone, and brick

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Restoration Products

The Isaac Ritter House (c. 1875). Repointed in NHL 3.5 by A&M Masonry of Arlington, WI.
The Isaac Ritter House in Galena, IL (c. 1875). Repointed in NHL 3.5 by A&M Masonry of Arlington, WI.

Lime mortar is the material of choice for historic masonry buildings. Flexible and breathable, lime mortar accommodates freeze-thaw cycles and prevents damage to historic masonry units. It is breathable and vapor permeable and it wicks water out of masonry walls which protects brick and stone from water damage.


NEW: Our Tips for Lime Mortar


  • All of our historic mortars can be custom blended with aggregates.
  • We offer custom color matching.
  • For large jobs we can deliver mortar via silo system for greater efficiency and economy. We are the only supplier in the country to offer this service for historic mortars.
  • We ship nationwide.

Saint Astier® pure and natural hydraulic limes (NHL) have been in production for over 150 years. The characteristics of the raw materials are unique and consist of an undisturbed layer of calcareous rock infiltrated mainly by silica with only traces of other minerals. Millions of tons have been used successfully around the world in a wide range of climates.

More about NHL


NHL 3.5

St. Astier NHL 2.0 | Detailed Information Sheet | MSDS Sheet

55lb bag – 30 bags/skid. Skid discount available.

This is a pure and natural hydraulic lime, feebly hydraulic, used when elasticity, low strength or high vapor exchange are desirable. It is recommended for finishes and mortars for weak stones.

St. Astier NHL 3.5 | Detailed Information Sheet | MSDS Sheet

55lb bag – 30 bags/skid . Skid discount available.


This is a pure and natural hydraulic lime, moderately hydraulic, recommended when moderate strengths and better freeze-thaw resistance are required. It is recommended for base coats and stone work.

St. Astier NHL 5.0 | Detailed Information Sheet | MSDS Sheet

66lb bag – 30 bags/skid. Skid discount available.

This is a pure and natural hydraulic lime, eminently hydraulic, specified when strength and high freeze-thaw resistance are necessary. It is recommended for slabs and mortars for hard stones.

Niagara Pozzolain Hydraulic Lime (PHL) is a high-purity Blended Hydraulic Lime using a high purity dolomitic limestone. Both PHL 3.5 and PHL 5.0 Blended Hydraulic Lime complies with ASTM 1707-09 (Pozzolanic Hydraulic Lime for Structural Purposes).


This mortar is designed for historic restoration work and it duplicates the original lime mortar, plaster, and stuccos originally used on many historic buildings. It is also suitable for sustainable construction projects such as strawbale and hempcrete. PHL provides breathability, flexibility and durability which is necessary for both historic masonry restoration and sustainable construction. Niagra PHL contains absolutely no Portland Cement, which helps reduce potential damage in historic applications where it was not originally used. It also offers exceptional plasticity and workability, and as a lime based mortar this product provides excellent water vapor transference. This is especially important in non-Portland cement based applications such as historic restoration or sustainable construction.


NEW: Our Tips for Lime Mortar


Pozzolain Hydraulic Lime 3.5 | Data Sheet

50 lb bag – 45/skid


The average 28 day strength is 500 PSI, which is optimal in historic and sustainable applications where weaker materials are desired.



Pozzolain Hydraulic Lime 5.0 | Data Sheet


The average 28 day strength is 750 PSI, which is optimal in historic and sustainable applications where weaker materials are desired.


50 lb bag – 45/skid

Slaking quicklime for a long period of time enhances the workability and body of lime used in construction and restoration applications.


We offer Niagara® mature lime putty, which is a high-purity dolomitic lime putty product that is fully slaked and screened for immediate use. This product is aged for a minimum of two months and has exceptional plasticity that is beneficial in dry mortars such as those used for tuckpointing. It is formulated to allow for volume proportioning equivalent to dry hydrate additions in compliance with ASTM C270.


Niagara® complies with ASTM C1489 (lime putty for structural purposes).


5 gal pail -24 pails/skid | Data Sheet


A sandstone sill repair performed using Jahn M70 Sandstone
A sandstone sill repair performed using Jahn M70 Sandstone. Photo: Pawel Nawrocki, Carving in Stone

This single-component, cementitious, mineral based mortar is designed for the restoration of limestone, sandstone, granite, bluestone, marble, concrete, terra cotta, and brick.  Unlike competitors’ products, Jahn has specifically formulated individual lines for each substrate . All Jahn repair mortars are vapor permeable and contain no latex or acrylic bonding agents or additives.


Only Certified Installers may purchase Jahn Repair Mortar. We offer a regular schedule of classes in the fall, winter, and spring to enable contractors, architects, and other professionals to obtain the required product certification. Our classes are two-day sessions and are discounted to $450.00 per person.

Learn More About Our JAHN Repair Mortar


Product Highlights


  • Single-Component: Mixes with water only, improving quality control and consistency of application.
  • Compatible Formulations: Compatibility of physical properties ensures that the plaster and substrate react to the environment in the same way.
  • Contains No Latex or Acrylic Bonding Agents: It protects the substrate by allowing salts, water vapor, and liquid water to reach the surface, preventing failure due to salt expansion or freeze/thaw cycles.
  • Tenacious Adhesion: Strong bonding capabilities without relying on synthetic bonding agents.
  • Factory Controlled: No field chemistry resulting in product variation.
  • Custom Colored Upon Request: Closely matches existing masonry. Choose from Standard or Custom Colors.
  • Certified Installers: Only installers with certification from Cathedral Stone Products can purchase Jahn Repair Mortars.

Basic patching procedures (PDF) English | Spanish


We have created the Chicago Color Collection, which contains 18 repair mortars selected just for Chicago. These colors match many of the most common stone, concrete and terra cotta materials found in Chicago and neighboring cities, and all colors are in stock at Henry Frerk Sons. This collection includes limestone, brownstone, concrete, terracotta, and marble mortars. We also offer in-house custom color matching and blending.




We carry an extensive selection of Jahn Repair Mortars, and custom colors are also available. The product line includes:

  • M70 Brownstone
  • M70 Sandstone
  • M70 Limestone
  • M90 Concrete
  • M100 Terra Cotta
  • M160 Bluestone
  • M160 Granite
  • M120 Marble

Click here for a full listing of product data sheets, MSDS, and specifications.

Standard color chart

All of our coatings and stains for historic masonry are breathable and vapor permeable. We offer a range of products from stains to coatings. Popular applications for these coatings include the use of custom tinted potassium silicate to match new masonry units to existing and “aging” new masonry and mortar to blend it with historic masonry.

An example of potassium silicate staining: we were asked to match the new brick (bottom) to the existing (top).

An example of potassium silicate staining to match new brick with existing. The bottom brick is a sample of the existing brick that we were asked to match. We applied stain to the new unit (top brick) and achieved a match to the existing brick (bottom).
We applied stain to the new unit (top brick) and achieved a match to the existing brick (bottom).

Coatings are also commonly used on terra cotta repairs. We offer the MasonRE Mineral Coating and MasonRE Terra Coating, which can be custom blended with colorants and additives such as mica to replicate the finish of historic terra cotta.

A custom matched terra cotta glaze with mica.
A custom matched terra cotta glaze with mica. The original terra cotta is on the left.

This product is a two-part system, with a clear liquid fixative and pigment additives. Potassium silicate is a highly breathable (92%) treatment that also helps consolidate friable masonry.  Blend the pigments into the fixative to create a custom colored stain that can be layered to achieve increasingly intense color. This product is highly effective for matching new masonry to old, creating the effect of staining, and adjusting the color of patches and other infill.


Potassium silicate stain is a proven material that has been used successfully for over a hundred years, and it is very long lasting and durable.


For best results, the stain must be continually agitated during the application process so that the pigments are properly dispersed.


We offer the Cathedral Stone product line, which includes:


Liquid Silicate ( 1 qt. jar / 2.6 gal. pail)

Stain Kit-Liquid Pigments

Stain Kit-Pigment Powder


Glaze Repair for Terra Cotta and Brick


Terra Cotta Glaze (formerly MasonRE Terra Coat) is a non-yellowing, water-based, acrylic coating that highlights the natural color of masonry by providing a clear, semi-gloss sheen. The treatment does not alter the natural texture of the surface, nor significantly affect the vapor transmission qualities of the substrate. Terra Cotta Glaze provides a durable finish to terra cotta and masonry surfaces.


Available in 1 gal or 5 gal. | MSDS | Data Sheet | Specification Guidelines


Features and Benefits


  • Water-Based Acrylic: For easier clean up.
  • Vapor Permeability Similar to Glazed Architectural Tiles
  • Tenacious Adhesion
  • Good Exterior Performance: Highly Abrasion-, Stain-, and Chemical- Resistant.


Surface Preparation

Use Jahn M100 or M125 to repair the clay body of terra cotta tiles where necessary. The repair mortar must cure for 14 – 28 days before the application of Terra Cotta Glaze . Apply Potassium Silicate Coating to the substrate and wait 24-48 hours before applying Terra Cotta Glaze . The surface must be clean, dry and free of oil, grease and other contaminants.



Mix well prior to application. Apply using airless paint spray equipment, brush or roller. When using an airless sprayer, use a 0.015 or 0.018 fan spray tip and reduce pressure to point of minimal misting or fogging to produce a wet application. Multiple applications may be necessary when applying to porous substrates or when a high gloss is desired; when this occurs, apply coats at right angles to each other with 4 to 6 hours between applications.


Curing Time

At 75° F (24 ° C): To touch 30 to 45 minutes. To handle: 2 to 3 hours. To recoat: 1 to 2 hours. Curing time varies with surface temperature, air movement, humidity and film thickness.


Clean Up

Clean equipment after use with mild detergent and water.



The ideal temperature conditions for applying Terra Cotta Glaze is between 60° – 90° F. If the ambient and substrate temperatures do not fall in this range, call a Cathedral Stone Technical Representative for special instruction.



Terra Cotta Glaze : Approx. 125 sq ft/gal

Coverage will depend on substrate absorption. Coverage rates are approximate and a test application must be performed to determine the exact coverage rate to achieve desired performance characteristics and aesthetic appearance before beginning a job.


Storage and Shelf Life

Store material in a dry area away from direct sunlight. Ambient storage conditions should be in the range of 35° F (2° C) to 100° F (38° C). Average shelf life is twelve months in original, unopened packaging at recommended storage temperature. Do not allow containers to freeze.


Technical Data

Volume Solids: 28%
Flash Point:>212° F

Mineral Coatings for Masonry


Cathedral Stone Products Inc. has developed their Potassium Silicate Coating (formerly MasonRE® Mineral Coating), afor use on all masonry (mineral surfaces), and over latex and acrylic coatings. Similar coatings have been in use in Europe for over 160 years and are now produced for the first time in North America. This coating technology combines the advantages of silicate/mineral and silicone coatings. Unlike latex and acrylic coatings, they form a molecular bond with the masonry substrate and the coatings are 92% vapor permeable.


Product Highlights


  • Specially formulated for masonry surfaces and over dispersion coating.
  • 92% vapor permeable.
  • Color fast.
  • Retards corrosion.
  • Fire retardant.
  • Withstands extreme climate conditions.
  • Water repellent.


Available in 1 or 5 gal. |  Data Sheet | Specification Guidelines


Surface Preparation
Potassium Silicate Coating should only be used by experienced users. This coating can be applied to any sound masonry or plaster surface. (Do not use on wood, plastic, or apply over oil or gloss coating.) The surface must be clean, solid, dry and free from efflorescence. The surface must be completely dry at the time of application. Potassium Silicate Coating is designed for vertical surfaces only. Horizontal surfaces, especially where water can pool, are not suitable for application. Cracks and spalls must be repaired and cured before coating. Cracks can be filled with Jahn M30 or M40 mortars. To ensure even penetration of the coating, make sure repairs have been made with repair materials that are compatible to the substrate. Temperature (ambient and substrate) must be at least 45° F (8° C) and below 90° F (32° C). Do not apply the Potassium Silicate Coating when precipitation is expected within 48 hours of application. Do not apply Potassium Silicate Coating when the temperature is expected to reach the dew point within 24 hours. Protect adjoining surfaces from splashes. Potassium Silicate Coating can only be removed while wet. Once Potassium Silicate Coating dries they CANNOT be removed.


When coating with dark colors, irregularly absorbing surfaces, or freshly poured concrete the substrate should first be treated with Cathedral Stone Green Etch S-309 (see Cathedral Stone Stripper Section for more information). The difference in substrate absorption can cause small color variations, which are more noticeable on darker colors. The S-309 will etch masonry to create similarly absorbing surfaces. Contact Henry Frerk Sons at 773-588-0800 for further questions on proper substrate preparation prior to coating.


Do not mix Potassium Silicate Coating with water. If Potassium Silicate Coating needs to be thinned out add Cathedral Stone Liquid Silicate until the desired consistency is reached. Mix Potassium Silicate Coating with a drill prior to use. When installing multiple units of coating, be sure to box-mix (Box-mixing is the blending of coating by pouring alternately between two containers.) This will help alleviate any minor color inconsistencies between batches.


Substrate absorption definition: The absorption must not be too high or too low for the coating to be applied correctly. Absorption can be tested by applying small amounts of water (drops) on the vertical surface to be coated. Normal absorption can be defined as the water absorbing into the substrate without beading on the surface. High absorption can be defined as water being absorbed so quickly that all traces of water seem to disappear rapidly. Low absorption can be defined as water laying or beading on the surface of the substrate (masonry must be etched in cases of low absorption).


Protect all areas not to be coated prior to application. Substrate must be completely dry before coating. Do not work when precipitation is expected within 48 hours of installation. The coating needs adequate time to bond to the substrate and moisture disrupts this curing process. Apply liberally and spread well, filling all pores and cracks. Work wet into wet. Potassium Silicate Coating should be applied with a short bristle brush. Brushing increases the absorption of the coating into the masonry, resulting in a longer lasting, more durable coating. Spraying and rolling the coating is possible. Allow the first coat of Potassium Silicate Coating to dry of at least 12 hours. Apply a second coat of Potassium Silicate Coating in the same fashion; work wet into wet.


Important Points


  • Make sure the substrate is completely dry and there is no expected dew.
  • Protect coatings from all forms of moisture: rain, dew, snow, etc. for 48 hours.
  • Temperature must be at least 45°F (8°C).
  • Protect any surfaces not to be coated.
  • Do not add water to Potassium Silicate Coating .
  • Always work wet into wet.


Clean Up
Place tools immediately in clean water when pausing work (15-30 minutes or more). Clean tools with clean water immediately after finishing work. Dried Potassium Silicate Coating is insoluble in water. Potassium Silicate Coating can be removed from non-porous surfaces with clean water while still wet.


Coverage depends on the absorption and structure of the substrate. Determine coverage with a trial application.

Normally absorptive, smooth surfaces with two coats:
One unit of Potassium Silicate Coating (approx. 5.0 gallons) will cover approx. 1200 square feet for a single coat and approx.750 square feet when two coats are applied. Coverage rates will generally be higher with darker color coatings.


Safety Information
Eye protection should be worn during mixing to protect eyes from splashing. Avoid contact with skin and mucous membranes. Work in well ventilated areas.


Storage and Shelf Life
Store in a dry area, away from direct sunlight. Storage conditions should be in the range of 40° – 80° F with low to average humidity. Average shelf life is six months in original, unopened packaging.


Notice: The information contained herein is based on our own research and the research of others, and it is provided solely as a service to help users. It is believed to be accurate to the best of our knowledge. However, no guarantee of its accuracy can be made, and it is not intended to serve as the basis for determining this product’s suitability in any particular situation. For this reason, purchasers are responsible to make their own tests and assume all risks associated with using this product.

keim silicate coatingsAbout Keim

With his invention of silicate coating systems in 1878, Adolf Wilhelm Keim founded the company which today is known worldwide as the leading specialist in mineral architectural protection systems providing sustainable solutions. KEIM is a specialist among generalists: in their specific field of “mineral silicate architectural protection systems,” they supply highly developed comprehensive solutions for exterior and interior surfaces.


About Keim Products

Using a combination of potassium and sol silicate, 100% inorganic, mineral pigments and fillers, KEIM offers superior bond strength while maintaining the highest levels of vapor permeability and color stability. Innovation is also part of KEIM’s history. In 2002, what is now the third generation of mineral silicate paints, revolutionized exterior historic coatings by using a sol-silicate binder. This combination of silica sol and potassium silicate not only provides bonding by silicification to mineral surfaces, but builds strong adhesive forces to previously painted, organic paints. This nanoparticle technology penetrates latex paint films to bond deep within the existing paint system and is the ideal repaint system when existing coatings cannot be removed.

Learn More About KEIM Mineral Coatings

KEIM Products

Exterior Stains & Coatings

Interior Stains & Paints

Concrete Systems

Natural Stone & Masonry Systems

Stucco & Plaster Systems

Mineral-Art Paints, Stains, and Glazes


To obtain a quote for KEIM products, please contact Randy Sabo, Outside Sales, at 312-833-5519 or at rsabo@hfsmaterials.com.

St. Astier Standard Lime Paint Colors

Vibrant and beautiful, the Le Décor – St. Astier lime paint range is the perfect compliment to lime plaster and suitable for most backgrounds. It can be applied to gypsum plasters, drywall, lining paper, cement and lime backgrounds, bricks, blocks and untreated timber.




St. Astier Lime Paint – Neutral (1 gal pail – 4/skid)

St. Astier Lime Paint  (5 gal pail – 4/skid)


MSDS | Users’ Guide | Technical Data | Specifications

Custom color matching and tinting is available