Saint Astier - Natural Hydraulic Lime

After years of research, global sourcing, and close collaboration with the world’s leading lime producers, we are proud to introduce a new chapter in our legacy:

Meoded proudly presents Saint-Astier® Natural Hydraulic Lime – the gold standard in sustainable restoration and durable construction.

SAINT ASTIER – NATURAL HYDRAULIC LIME

Saint-Astier® is a family-owned business with a rich heritage spanning over four generations, dedicated to producing high-quality Natural Hydraulic Limes. They source their exceptional limestone from their own quarry, a vast 350-hectare underground deposit known as the ‘Cathedral of Limestone,’ ensuring unparalleled and consistent mineralogical quality even at depths of 200 meters. Renowned for its purity and absence of additives, Saint-Astier® Natural Hydraulic Lime (NHL) is a trusted choice for historic restoration mortar, stucco, and plaster, avoiding the use of harmful Portland cement. For over 150 years, Saint-Astier® NHL has been used worldwide to conserve, restore, and enhance various structures, from historical monuments and listed properties to vernacular and modern architecture.

Saint-Astier® NHL 2

The Chalk Lime

Saint-Astier® NHL 3.5

The Versatile Lime

Saint-Astier® NHL 5

The Roman Lime

Why Choose Saint-Astier® Natural Hydraulic Lime (NHL)?

Trusted for over 160 years. Made in France. Loved worldwide.

Saint-Astier® NHL is the gold standard in lime binders—ideal for both historic restorations and sustainable new builds. Here’s what makes it stand out.

Unlike some tan or clay-heavy NHLs, Saint-Astier® contains lower iron and alumina levels—meaning no risky salt expansions, alkali-silica reactions, or hidden ingredients like gypsum or cement. You get a cleaner, more stable material that performs for the long haul.

Saint-Astier® keeps the “Free Lime” content just right—enough to self-heal cracks and improve freeze-thaw resistance, but not so much that it weakens the mortar or absorbs too much moisture. Some brands have 65–88% free lime, which makes mortars soft and spongy. Saint-Astier® hits the sweet spot.

Many producers have to manipulate their lime with fillers or re-burnt materials to meet standards. Saint-Astier® doesn’t. Their natural limestone deposit is so consistent and high-quality that no artificial tweaking is needed. What you see is what you get.

Need to adjust your mix? No problem. Saint-Astier® NHL retains 80% of its strength even after being reworked within 24 hours—meeting both European (EN 459) and American (ASTM C-141) standards. Most other NHLs can’t do this.

Saint-Astier® NHL 3.5 and NHL 5 can be mixed with sea water—yes, sea water!—without risk of damage. Perfect for coastal builds or islands where fresh water is limited. Over time, it gets even stronger.

Traditional Type-N or Type-O mortars with even a touch of Portland cement can damage old brick and stone. Saint-Astier® NHL is 100% Portland-free, making it ideal for sensitive restoration work.

What’s in the bag is what’s on the label. Saint-Astier® is true Natural Hydraulic Lime—no blends, no cement, no additives. Just add sand and water, and you’ve got a top-quality mortar.

Why Professionals Trust Saint-Astier®?

Architects, conservators, and builders worldwide trust Saint-Astier® for its reliability, consistency, and unmatched performance. It’s not just another lime—it’s the benchmark others are measured against.

Saint-Astier® NHL The natural choice for those who demand the best.

Natural Hydraulic Lime

Lime is available in two primary forms: Hydrated Lime and Hydraulic Lime.

This is the most widely used type of lime. It comes either in a powdered form, such as Type N, NA, S, or SA, or as a paste known as Lime Putty. While Hydrated Lime boasts excellent physical and aesthetic properties, it has significant limitations in construction. It sets only through carbonation (the re-absorption of CO2), which restricts its use to thin layers. It is impractical for use in scratch or brown coats in plaster but can be highly effective as a finish coat, often requiring blending.

Hydraulic Lime, although chemically similar to Hydrated Lime, has the advantage of setting initially with water, similar to cement, and then completing its set by absorbing CO2. This property simplifies its application, although it still requires basic care, such as controlling the amount of water used, ensuring good sand quality, and proper tarping. The labor costs for applying Hydraulic Lime are comparable to those for normal stucco installations. For example, the hydraulicity of St. Astier lime is a result of the natural raw materials used.

Hydraulic properties in Hydrated Lime can also be achieved by adding cement, pozzolans, or other materials. However, introducing foreign chemical elements can have immediate or long-term negative effects, so it is advisable for users to avoid such hybrid products.

Natural Hydraulic Lime

Lime is available in two primary forms: Hydrated Lime and Hydraulic Lime.

Concrete plasters composed of cement and limestone offer outstanding durability and strength. Their blend ensures resistance to cracking and weathering, making them suitable for diverse environments, both indoors and outdoors. The cement component provides robust structural stability, while the limestone contributes to a resilient and long-lasting finish. As a result, our concrete plasters maintain their aesthetic appeal and structural performance even under harsh environmental conditions.
Concrete plasters made from a blend of cement and limestone offer excellent breathability, allowing moisture vapor to escape effectively. This characteristic helps prevent trapped moisture, reducing the risk of issues such as mold growth and deterioration. The breathable nature of these plasters ensures that surfaces remain healthy and resilient, contributing to a stable and long-lasting finish.
Their versatility allows for various finishes, from smooth-modern to textured and rustic. Whether used in residential, commercial, or industrial settings, these plasters can be customized to meet diverse aesthetic and functional needs, making them an ideal choice for numerous projects.
The resistance to moisture and weathering allows these plasters to maintain their appearance and structural integrity with minimal upkeep, ensuring long-lasting performance and ease of care. Once sealed, these finishes become highly washable requiring minimal maintenance and making them easy to clean with just mild soap and water.
The blend of limestone and cement has been used for centuries, from the richness of Roman architecture to traditional building techniques around the world. Its enduring popularity is a testament to its strength, versatility, and aesthetic appeal, continuing to be a preferred choice in both historical restorations and modern construction.

What is Natural Hydraulic Lime?

Hydrated Lime (also known as calcium lime, air lime, high calcium lime):

This is the most widely used type of lime. It comes either in a powdered form, such as Type N, NA, S, or SA, or as a paste known as Lime Putty. While Hydrated Lime boasts excellent physical and aesthetic properties, it has significant limitations in construction. It sets only through carbonation (the re-absorption of CO2), which restricts its use to thin layers. It is impractical for use in scratch or brown coats in plaster but can be highly effective as a finish coat, often requiring blending.

Hydraulic Lime:

Hydraulic Lime is a vastly superior material to hydrated lime for most construction applications, especially where strength, durability, and performance are required. While it is chemically related to hydrated lime, its key difference—and major advantage—is that it sets through a combination of hydration (with water) and carbonation (with CO₂). This dual-setting process gives hydraulic lime significantly better performance in a wide range of conditions.

Unlike hydrated lime, which sets slowly and only in contact with air, hydraulic lime can set in damp, cold, or even underwater environments—making it ideal for structural applications, thicker plaster layers (including scratch and brown coats), exterior use, and areas with high humidity.

There are three main grades of Natural Hydraulic Lime (NHL):

  • NHL 2 (feebly hydraulic) – suitable for interior plastering and softer masonry

  • NHL 3.5 (moderately hydraulic) – versatile for general use in historic restoration and modern construction

  • NHL 5 (eminently hydraulic) – used for more exposed or load-bearing work like foundations or chimney stacks

Hydraulic lime maintains breathability, flexibility, and compatibility with traditional materials—qualities that are essential in the restoration of historic buildings and beneficial in modern eco-conscious construction. It provides strength without sacrificing vapor permeability, reducing the risk of trapped moisture and associated damage.

High-quality hydraulic limes like St. Astier NHL derive their hydraulic properties naturally from the specific composition of the limestone from which they are produced—no additives or cement are required. This results in a more stable, reliable, and long-lasting material than so-called “hydraulic” blends made by adding pozzolans or cement to hydrated lime, which can compromise performance and building longevity.

In terms of application, hydraulic lime can be used by the same tradespeople who apply stucco or plaster. While some care must be taken with mixing and curing, the learning curve is small, and the benefits are significant. The final result is a more durable, breathable, and aesthetically pleasing finish that will stand the test of time.

Quick Comparison:
NHL 2 vs NHL 3.5 vs NHL 5

Feature / Property

NHL 2
(Feebly Hydraulic)

NHL 3.5 (Moderately Hydraulic)

NHL 5 (Eminently Hydraulic)

Compressive Strength (28 days)

~2 MPa

~3.5 MPa
~5 MPa
Setting Time
Slow

Slow

Moderate
Flexibility / Elasticity
High
Balanced
Low
Breathability
Very High

Very High

High

Suitability for Soft Masonry
Excellent
Good
Limited
Weather Resistance
Low–Moderate

Moderate

High

Use in Marine/Coastal Areas

Not Recommended

Not Recommended

Occasional Use
Best For
Historic interiors, soft masonry
Exterior plasters, moderate loads
Foundations, chimneys, heavy-duty work

Need More Information? Talk To Our Experts

Reach us at (323) 308-2600
We will be more than happy to answer your questions.