How to repair marble cracks step by step
Marble looks spectacular in its natural state and can withstand substantial structural pressure. However, due to its porous nature, it can develop cracks for a variety of reasons, including: dropping items on the surface; applying a lot of weight to the surface over an extended period; and changing temperature due to appliances changing the temperature of the adjacent surface. In order to successfully repair a marble surface, you will need the right equipment/tools/materials; surface preparation; and very specialized knowledge about the specifics of the repair work upon the cracked marble surface area. Because of these common characteristics of all cracked marbles, you will need to take a different approach to repairing the cracks based on the size of the crack, the method of repair used (e.g., epoxy or polyurethane), and the amount of time required to complete the repair. There are two primary steps in repairing cracked marble surfaces: 1. Identify what type of crack you have and how large it is. Identifying the type of crack will allow you to select the correct way to repair the crack; once you have that information you also will be able to assess how large a piece of marble you are going to need to patch in order to make up for the missing piece of marble; and the size of the patch you will need for the area to be repaired for any given time frame. 2. Prepare the area to receive an adhesive/bonding agent by properly cleaning and preparing the surface of the area where the bonding or adhesive agent will be applied. Creating a clean, dry, and well-prepped surface is vital for a successful bond to occur when it is bonded to the surface of the cracked marble; no matter what method is used to repair the cracked marble, if it is not bonded correctly, it will fracture again shortly after the repair is complete (regardless of type).Surface area preparation entails cleaning the area to be repaired with a neutral pH cleaning product. The area must be cleaned before you can apply any bonded or adhesive surface agents. To clean the surfaces completely, all mold, dirt, grease, or other contaminants, exist on all surfaces must be removed and dried prior to applying any adhesive.
Selecting repair materials is critical when repairing marble. There are three types of repair materials used most often when repairing marble: epoxy resin (clear or tinted) – Typically used when there is a structural problem or when a very strong bond is desired; polyester resin – Typical drying times are faster than the other two repair materials but have lower tensile strength than epoxy materials; marble filler putty – Typically best for very shallow non-structural cracks. To achieve the desired natural marble appearance you will want to use color matched or tintable epoxy material for repairs to marble.
Once you have selected your materials for repairing a structural crack, to maximize your adhesive performance; you will have to create the crack in order to achieve the best adhesive bond. To best create the crack; Using a small blade or rotary tool, create a small “U” or “V” shape in the crack to provide maximum adhesion for the adhesive; Use either an air compressor or soft brush to remove all debris and loose material from the surface area;and wipe down the area you will be repairing with acetone to remove any oils or other contaminants.Taking all of these necessary steps will increase how deeply adhesive will travel into the crack and ultimately improve how well the adhesive bonds to the marble. 5. Mix Adhesive Product As Directed Follow manufacturer instructions for mixing together resin and hardener as well as following proportion directions. Pigment (optional) may be used to match existing marbles. Be aware that open time (i.e., time you have to apply adhesive) will be limited based on the type of adhesive being used and will not exceed the maximum time limits for mixing operations. 6. Use Adhesive to Fill Marble Opening Use a putty knife and/or syringe to fill the crack with adhesive while ensuring no air pockets are left in the adhesive after the crack has been filled to completion. Overfilling the crack slightly will allow the adhesive to shrink as it cures to a solid state, which is required for adhesion strength. Use a heavier grade of adhesive (knife grade) when applying vertically to prevent sagging while curing. 7. Remove Excess Adhesive Any excess adhesive should be removed immediately from the marble and surrounding area using clean rags or solvent to prevent future adhesion between marble surface and other materials in contact with it. In addition to cleaning up after using an excess of adhesive, it is also advisable to tape off areas where the adhesive may spill or drip onto nearby surfaces, to provide added protection from unwanted adhesion to other materials. 8.Let the Glue Cure per Manufacturer’s Directions
All adhesives must be allowed adequate time to cure (usually: 24-48 hours) as directed by the manufacturer. Under no circumstances should you use or put weight on the repaired area until the adhesive is completely cured. Periodically check the temperature and humidity of your marble while applying and during the adhesive cure period to maximize strength of the repair using professional epoxy/adhesive stone repair products.
Sand and Polish
You can start sanding after the adhesive has cured successfully. Use fine grit sandpaper to begin with (400-800) and use higher grit sandpaper (to 1500-3000) until you achieve the desired finish. You can polish the finished work surface using a marble polishing powder, compound, or marble buffer in order to achieve optimal shine after completing the repair. Polishing the finished work surface helps to blend into the surrounding marble.
Protect the Marble Surface
Use a quality stone sealer to help protect the repaired area. Sealers will protect against moisture and stains. A part of your regular maintenance during your marble’s life, will be to reapply sealer on an ongoing basis.
Common Mistakes to Avoid
1. Using the wrong type of adhesive (i.e. standard versus specific type of epoxy for stone surface repairs).
2. Incorrectly prepping the substrate for the adhesive application.
3. Using an adhesive that is a different colour than the surrounding colour when using a stone adhesive for repair purposes.
4. Duress will attempt to decrease the cure time by placing additional weight on the repaired surface.
5. Over-sanding the marble surface will remove some of its original finish prior to polishing it.
Contact a Professional
If you feel you need a professional to assist you, you should do so if: (1) Your cracked marble will structurally compromise the integrity of the marble; (2) Your cracked marble is of significant value or highly visible; or (3) You would like to have state-of-the-art tools and procedures used to perform an almost invisible complete repair.
Summary
Repairing marble the right way with a consistent and methodical approach will give you back the original aesthetic/original structural integrity of your marble. Repairing both cosmetic and structural cracks of all sizes with a professional marble repair technician will give you a repair that will be more attractive than one completed by an amateur and will retain its attractiveness for much longer than an inexperienced repair.
