"Repair of stone is an accepted practice and will be permitted. Some chipping is expected; repair of small chips is not required if it does not detract from the overall appearance of the work, or impair the effectiveness of the mortar or sealant. The criteria for acceptance of chips and repairs will be per standards and practices of the industry unless other criteria are mutually agreed upon by the limestone supplier and the architect." Indiana Limestone Handbook
The handling of damage to and repair of Indiana Limestone can make the difference between a good job and a marginal one. Over the years, limestone fabricators have developed handling methods which reduce the incident of damage in the mills; where damage does occur and is judged to be repairable, it is industry practice to make the repair and ship the affected stone.
Damage occurring in transit, in the unloading/stacking/installation process, can usually be repaired satisfactorily by masons at the job, often using materials supplied by the stone fabricator.
The Indiana Limestone Institute recommends that small chips and snips be left alone. Usually they will not detract from the appearance of the finished work, especially if they are not at or near eye-level.
Larger chips may be repaired using cementitious materials made for the purpose. This is the kind of material ordinarily used by the fabricators. Skillfully placed, these repairs are nearly invisible and are suitable for use at a building's upper areas, or those areas not seen at close range.
When the chip can be saved, it is usually possible to replace it using either a thermo-setting resin adhesive, or cyanoacrylate "superglue."
If the chipped area is larger, or if it is in a critical location, a "dutchman" can usually maintain the stone's usefulness. This is a separate piece of stone cut to fit tightly in the squared-up void.
Broken corners can usually be repaired satisfactorily using thermo-setting adhesives. Occasionally, depending on the location of support surfaces in relation to the damage, dowels, plates or angles may be required in addition. The resulting hairline joints are ordinarily not objectionable, and such repairs are structurally sound if correctly done.
Cracked stones are occasionally reparable, although when a stone shape has been so severely shocked as to develop a crack, its integrity may be suspect. Stones mounted to frames that resist both gravity and lateral loading are often the exceptions to this caution, depending on how the stones are affixed to the frames. This fact suggests that repairs to cracked stones may involve the addition of metal framing. Thermo-setting resins are the repair material of choice here.
Reasonable care in handling will reduce or eliminate the need for repairing Indiana Limestone. Most stone shipments arrive at the site in good order, and by far the majority of stones reach their final position in the building with no damage. For trouble-free projects, contractors are urged to follow the handling instructions listed in ILI's publication, The Contractors Handbook on Indiana Limestone.
Where repair is seen as necessary, a booklet entitled Repairing Indiana Limestone can be helpful. Copies are available from ILI or its member companies.
Indiana Limestone will give the greatest satisfaction when it is handled as carefully as marble, aluminum or metal panels, granite, glass, slate, or any other material that provides a finished surface when it arrives at the job.