How long will a sealer last? What about the warranty claims made by manufacturers? There are plenty of claims, but it really comes down to proper application and maintenance. Homeowners should be aware that most warranties take effect ONLY when an accredited applicator seals your stone. Be sure that the applicator doing the work is reputable. It should be noted that any sealer on the market today that offers a warranty, the homeowner and/or applicator read what is warranted. Read the fine lines.
The wear and tear of daily use, exposure to the elements and maintenance plan all play a part in how long a sealer will last. A simple water porosity test to check the seal can be done by the customer:
Drip a tablespoon of water on the stone surface. Be sure to time the test. If the puddle darkens quickly, then sealing granite countertops is required. If it takes 3 or 4 minutes to darken a good impregnator sealer should be applied, sealing every 3-5 years should be fine and stains won't be an issue unless a staining material sits on the surface for a long period of time. If the puddle doesn't darken, then you have a stone that is next to impossible to stain. Sealing granite countertops in this category is really not necessary.
Assuring the customer that their stone surface is protected is the primary reason many professionals recommend applying granite sealer when in doubt or even if it really isn't needed.
For most granite material applying a sealer even when not needed won't present a problem. However, some dark granite material such as blacks and greens are very dense and if a sealer is applied, it sits on the surface without sinking into the stone and can noticeably dull the appearance. This can lead to having to refinish the stone or using strong chemicals to strip the surface. The best way to determine if the darker, denser stone material needs to be sealed is to drop a small amount of oil on the surface( in an inconspicuous area) and let it sit overnight. If the oil wipes up leaving no stain, then sealing isn’t necessary.
