Do You Need To Seal? Here is the quick test to determine if you need to seal. Simply place drops of water randomly around the surface. This must be drops, not a splash or a cupful. And you should be testing each different kind of component (tile, grout, divider strips, etc.). If the surface darkens in a minute or so, that means the water is penetrating. The whole drop of water does not need to absorb. Just the fact that it penetrated a little bit as indicated by the darkening is all that matters. Stains usually come from water based or petroleum based liquids. The surface tension of a water drop creates less ability to penetrate into a surface than a drop of a petroleum based liquid. Therefore, if water bourne staining material can penetrate a little, a petroleum bourne staining material will be worse. So then, if you see the darkening from a water drop, you do need to seal - no matter what you were told to the contrary. If some areas show darkening and others do not, some areas are susceptible to staining. Choose a sealer based on the characteristics of the least absorbent portion so that you can apply evenly to the entire floor. You have a sizable investment in the project, so it makes sense to protect it. A good seal job will accomplish numerous things beyond the appearance. Sealers have two major purposes: Protect the material being sealed Meet finished appearance expectations (i.e., high gloss to no gloss, some or no color enhancement, help disguise color variances or minor stains) However, there are many benefits available beyond these, such as: low maintenance (never having to re-apply a sealer) efflorescence prevention easy periodic floor cleaning stabilization of soft materials (Mexican tile, soft stones, weak grout, etc.) stain and color problem masking Achieving these additional benefits only requires making the correct choices in the beginning and following the information contained here and on the packaging. Protection! Even if you don't want to change the appearance, it certainly makes sense to protect your expensive project with low cost insurance through sealing. Seal against potential staining and traffic damage. Appearance You can effect the finished appearance of your project by selecting an appropriate sealer. See the "Surface Types" page. Aldon manufactures such a great variety of sealers because users demand a wide range of possible finish characteristics for all the tile and masonry products now available. And one or two sealers will not meet all those finish needs.   When You Should Not Seal! If You Are Not Going To Follow The Aldon Package Directions These directions have been refined over years of assisting homeowners and contractors to achieve 100% successful installations in the easiest, most foolproof manner possible. They are a recognition of how people have encountered unforeseen problems because of unknown job site conditions. Following the package instructions exactly achieves applications that will automatically compensate for most job variables and prevent problems known and unknown from occurring. Read a label and you will see detailed word pictures of what you are accomplishing and why. Don't overuse or underuse the sealer, apply as described and your risks will approach zero and your success 100%. If You Are Not Sure Of What You Are Sealing! If your surfacing does not appear in the "Surface Types" section, do not seal. See the page regarding identifying surfaces in this section. If doubt still exists - see the "Contact Info" page and email technical services. If You Are In A Hurry And Are Not Willing To Patch Test! No matter how careful you are in your research, there are so many potential variables in a typical installation, you really need to patch test before doing the complete job. If The Surface Does Not Look Pleasing Now Don't seal until it looks exactly the way you want it to look forever. If there are some appearance problems see the pages here for cleaning and problem solving. Aldon sealers designated to have color enhancing effects will help greatly after you have done everything recommended and it is still less then perfect. These sealers provide a degree of masking and disguising of color differences remaining from stains. If There Is Moisture Coming To The Surface Don't seal until you have read the section on efflorescence. Water sources can be from underneath (pipe leaks, saturated soil) or above (sprinkler or rain water entering through cracks or flashing problems).