Jahn M25

Lime Mortar

This hydraulic lime mortar is designed for the restoration of many masonry surfaces. Jahn M25 is completely vapor permeable and contains no latex or acrylic bonding agents or additives. M25 can be used for patching, pointing, or injection. M25 is formulated for compatibility of many masonry substrates and is available in standard and custom colors.

Features and Benefits
*Single-Component: Mixes with water only, improving quality control and consistency of application.
*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. Water Based: Environmentally and user safe. No solvent clean-up or disposal problems.
*Custom Colored Upon Request: Closely matches existing masonry. Choose from Standard or Custom Colors.

Application Procedures

Surface Preparation
Surfaces to receive M25 must be sound and free of all dust, dirt, grease, laitance and/or any other coating or foreign substance which may prevent proper adhesion. Remove all loose and deteriorated masonry from the repair area using manual or pneumatic cutting tools. Do not install M25 on unsound masonry.

Mixing
The mixing ratio is approximately 3 1/2 to 4 1/2 parts powder to 1 part water by volume (or until material is easy to spread), depending on temperature and humidity. More water may be required as ambient temperature rises. The mixing may be done by hand or by mixer, stirring until the mortar is thoroughly mixed. The mortar should be the consistency of putty. M25 may also be mixed using a slow speed drill (400 - 600 rpm) equipped with a Jiffler-type mixing paddle. For best results, add the powder to the water slowly. The working time will vary, depending upon wind, temperature, and humidity. The use of excessive water in the mixture will lighten the color of the repair.

Application
Patching: Moisten the substrate using clean water. Jahn Mortar should be applied to a well-dampened surface (with no standing water). If the surface is allowed to dry out before applying M25, this step must be repeated. This is very important.

Apply the mortar into the patch using 1/4 " lifts. Be sure to compact each successive layer fully. The material should be left to dry between layers. Build up material beyond the surface of the original stone. The waiting period before finishing will vary, depending upon wind, temperature, and humidity. After achieving initial set, scrape away excess mortar until the desired profile is reached.

For a smooth finish, build up material flush to surface. After the initial set, trowel the patch to achieve desired finish. If the repair is finished immediately, "floated", "troweled", or performed in rainy weather conditions, the color will lighten.

Pointing: Moisten the joint using clean water. If the surface is allowed to dry out before applying M25, this step must be repeated. This is very important. The mortar should be workable, but as stiff as possible. The mortar should be applied using appropriate pointing tools Apply the mortar into the joint using 1/4" lifts. Be sure to compact each successive layer fully. Make sure each lift is thumbprint hard prior to application of the next lift. Finish the joint to match existing profile.

Injection: Immediately before injection, moisten interior of the crack by flushing with water. If the crack is allowed to dry out before the grout is injected, this step must be repeated. This is very important.

Transverse Cracks
Drill a series of injection ports in the center of the crack. These ports should be drilled in a downward direction. Seal the crack with removable, non-staining clay, sealant, or caulk.

Inject grout into the lowest port and continue until it flows freely from this port and other ports at the same level. Seal ports using non-staining clay, sealant, or caulk and proceed in identical fashion until the crack is filled. Clean up overflow and runs immediately with clean water while still wet. Do not allow to dry on masonry.

Lateral Cracks (Delaminating Layers)
Drill a series of injection ports in a square configuration (90° angles) on the face of the substrate to create a "drill frame". Ports should be drilled in a downward direction. Wash the surface and interior of the crack using clean water to remove as much dust and loose material as possible. Any dust or debris remaining between the layers will impede the flow of the grout. If this is the case, more holes will be required to attempt to fill all hollow areas.

Inject grout into lower left port and proceed until it flows freely from this port and other ports at the same level. Seal ports using non-staining clay, sealant, or caulk. Inject grout into lower right port and proceed in identical fashion. The order of injection is lower left, lower right, upper left, then upper right. Clean up overflow and runs immediately with clean water while still wet. Do not allow to dry on masonry.

Curing
Periodically mist M25 repairs using clean water until the mortar has hardened. The timing for initial misting will vary with ambient conditions. Hot, dry conditions may require misting in 30 to 60 minutes. Cooler, damp conditions may require waiting several hours before beginning the curing process. Mist several times a day. Should access to the repairs be impossible over a period of time, plastic may be used to cover them temporarily. The application of plastic, however, does not remove the need for normal curing techniques.

Clean Up
Remove uncured mortar from the perimeter of the repair before it dries using clean water and a rubber sponge. Repeat several times with clean water to prevent a halo around the patch (staining of adjacent masonry). Cured mortar may only be removed chemically or mechanically.

Safety Requirements
It is recommended that safety goggles, gloves, and a dust mask equipped with P-2 filters (or equivalent) be worn for protection while mixing.

Limitations
* Do not apply Jahn Mortar to a frozen or an exceedingly hot substrate. The applied mortar must be protected from extreme heat, freezing, excessive wind, direct sunlight, and rain. Ambient temperature range should be 40° F to 90° F with low to average humidity.
* Do not add bonding agents to Jahn Mortar or use them as surface preparation materials.

Packaging and Coverage
M25 is available in 2 and 5-gallon pails. This will cover 0.2 cubic feet and 0.5 cubic feet respectively.

Storage And Shelf Life
Store material in a dry area away from direct sunlight. Ambient storage conditions should be in the range of 40° F to 90° F with low to average humidity. Average shelf life is 6 months from when it leaves Cathedral Stones' warehouse if it is kept in original, unopened packaging.

Technical Data
Jahn M25 - Lime Mortar

HARDENED PHASE
Compressive strength	808 psi
Tensile bending strength	318 psi
Modulus of elasticity	807 ksi
Specific gravity	1.74

These values are variable

Warning Not for internal consumption. Keep out of reach of children and animals.

Product data last updated 8/2002