You know grout is sealed if water beads up on the surface and doesn't soak in or darken the grout; if the grout absorbs water and turns dark, it's unsealed and needs reapplication. The most reliable method is the water test: spray or drip water onto the grout, wait a few minutes, and observe if the color changes or stays the same, indicating protection or absorption, respectively.
Unsealed grout is vulnerable from the start. Water gets in, dirt sticks, and bacteria thrive in the damp environment. It's why grout lines start out light gray or white and end up looking dark, uneven, or stained.
When grout is not sealed in time, grime and water can seep into it, causing cracks on your tiles and forcing them to break at a certain point. By sealing your grout, you get to prolong your tile surface's lifespan and minimize damage to a considerable extent.
Grout is naturally porous and will stain easily; as a result, all grout needs to be sealed once it has had time to properly cure. However, not all tiles need to be sealed – see below for information on what types of tiles need to be sealed.
Sealing your grout is a must, especially in moisture-prone areas or when working with a light-colored grout. The only type of grout that doesn't need sealer is epoxy, which is inherently pre-sealed. Grout sealers typically come in two forms-- spray-on sealers and applicator sealers.
Even if the grout appears to be hard, achieving the correct color will require time for excess moisture to evaporate. We know you've been looking forward to seeing your finished product, but don't get ahead of yourself! We recommend waiting for at least 48 hours after installing a grout before you apply a sealer.
Although it may require a little patience, sealing grout is an extremely simple process, and there's no need for any specialist tools. However, for easy application and professional results, make sure you choose the right product for the job. Here are a few tips on selecting grout sealer.
Grout tends to wear away more quickly when it is not sealed, so it will crack, discolor and become hard to manage when cleaning. This will force you to replace it more often than if it was sealed, leading to higher costs overall.
SINGLE COMPONENT GROUT
It shares many of the benefits of epoxy grout: it has excellent color consistency, doesn't need to be sealed, resistant to breakage and chemicals, resists mold and mildew, is stain resistant, and doesn't effloresce.
Sealer is not a waterproofer it is considered a moisture barrier and stain resistant. In over 30 years demoing tile showers the only time water gets behind grout is if it cracks and doesn't get repaired. Grout sealer is also not a one and done thing it wears and needs reapplied.
You generally should not grout directly over old grout for longevity and adhesion, as it often leads to cracking and peeling; instead, you must first remove a significant portion (at least 2mm) of the old grout, thoroughly clean the area, and then apply the new grout to ensure proper bonding and a lasting finish. Special rejuvenation grouts or epoxy grouts might require less removal, but scraping out most of the old material is the best practice for standard grout.
Not Foolproof. Even with sealing, grout can still get dirty if not cleaned regularly. It reduces but doesn't completely eliminate the risk of stains and mold.
When grout is not properly sealed, moisture can penetrate the surface, weakening the bonds and causing cracks. Over time, this can lead to mold growth and even loosen tiles. Regular sealing is essential to protect grout from moisture-related damage.
Vinegar can indeed ruin grout.
Once lodged in these spaces, vinegar will corrode grout with the passage of time. The grout will eventually wear off. So you should take not to apply vinegar for cleaning purposes if you have unsealed grout in the area.
One of the first signs of a sloppy job is grout lines that don't line up, or messy cuts. These are obvious aesthetic signs that the contractor is cutting corners. Even worse and less obvious are uneven tile surfaces, what's known as lippage.
Install professional-looking tiles by learning from these common grouting mistakes.
Unsealed grout is susceptible to moisture penetration, which can lead to the deterioration of the grout itself. Over time, this degradation can result in weakened grout lines and tiles that may become loose or crack.
Try hydrogen peroxide: You can use this product on its own and apply it with a spray bottle, or you can mix it with baking soda for a home-made grout cleaner. Let the peroxide sit on the grout surface before scrubbing and rinsing.
How to Seal Grout
Most tile contractors charge per square foot to seal grout; the more area you have, the more you can expect to pay. For example, a 160-square-foot area may cost $1.56 per square foot, but a larger area may cost as much as $2.00 per square foot.
Unlike a thin, clear sealant that wears away quickly, grout color sealing utilizes a durable epoxy-based formula. This advanced sealant penetrates the porous grout and creates a non-porous, permanent bond.
The 1/3 rule for tile is a layout guideline recommending you stagger long, rectangular tiles by only one-third (33%) of their length, not the traditional 50% (half), to minimize "lippage" (uneven tile edges) and create a smoother, more visually appealing surface, especially with large format tiles that can naturally bow during manufacturing. Instead of a centered "brick joint," this method creates a diagonal "stair-step" effect, reducing the height difference where a high tile center meets a low edge.
MAPEI recommends using UltraCare Penetrating Plus Stone, Tile & Grout Sealer or UltraCare Penetrating Plus SB Stone & Porcelain Tile Sealer on all cement-based grouts, porous natural stone, clay tile, cement-based tile, quarry tile, brick and polished porcelain tile.