DEAR TIM: The grout on the wall and floor ceramic tile in the master bathroom of our new home was supposed to be the same color. The floor grout is much lighter than the walls. The builder and tile company agree it is a manufacturing defect as the batch of dry grout was mixed wrong at the factory. The tile company wants to stain the floor grout to match. What is the best way to stain tile grout? What could have been done to prevent this problem? Jennifer H., Virginia Beach, VA

DEAR JENNIFER: Years ago, I had the same thing happen to me. When I left the tile store I made sure the batch numbers on the grout bags were identical and even from the same pallet. I assumed that since the bags were next to one another on the pallet the contents had to be from the same giant mixing hopper at the factory. Well, don't ask me what went wrong, but I ended up with two totally different colors once the grout dried. It was a huge problem.

Grout colors can be changed successfully and permanently. I had to do it in my own home on my Entrance Hall slate floor. When I built my home, the salesperson at the tile store sold me a super-duper grout additive that was supposed to make the grout stronger and more stain resistant. The additive was a milky latex product that was mixed with the dry grout. I added it exactly as was told by the additive and grout manufacturers and the end result was a splotchy mottled deep gray grout instead of the jet black color I was supposed to get.

A great brush with the right stain allows you to make grout lines look fantastic.

Oil stains, in my opinion, work better than water-based ones because the oil solvents allow the pigments to penetrate deeper into the hard cement-based grout. Be sure your contractor gets an oil based grout if at all possible. The neat thing about oil-based grout stains is they can be applied to grout of any age. You can stain grout 30 days or 30 years old with the same fantastic results.

For the staining job to be a stunning success, your contractor needs to follow a few simple steps. The grout must be completely clean and dry. New grout should cure at least 30 days before staining. Verify this with the product you buy. The label instructions always mention minimum cure times. You can deep clean dirty grout using an oxygen bleach solution. Oxygen bleach will not remove any of the grout's existing color, but it will get rid of all dirt and grime. This non-toxic solution works best if you allow it to soak for one or two hours before lightly scrubbing the floor.

The hardest part of the job is applying the stain. You must do it carefully with certain flooring materials. Tiles that have a high-gloss glaze are the easiest to stain. If a little stain gets on the tile, it can usually be wiped off the tile with little effort. But tiles with little or no glaze and slate can be a nightmare to stain. You must slowly and carefully apply the stain to just the grout. I find that a stiff artist's brush with a square tip and 1/4 inch wide bristles works best. You do not want a brush that has limp bristles. You need a stiff bristle brush that will give you excellent control.

Once the grout is dry, you may choose to seal it. It is not necessary, but it does help keep the grout clean. The sealers minimize the amount of liquid that can penetrate the grout.

Your problem could have been easily avoided. After my nightmare years ago, I always bought one extra bag of colored grout. Before I started grouting, I took all of the bags and emptied them into a clean wheel barrow. I blended the dry powdered grouts together until they were well mixed. The grout was then transferred to clean dry plastic buckets with tight fitting lids. This method produces grout that is absolutely uniform in color when it dries.

Grout stains really work and work well. For some reason they are not talked about very much. All too often people re-grout to get rid of ugly grout when many times a simple stain will rejuvenate a ceramic tile job.

The best part is that colored grouts can enhance colored ceramic tile. Frequently tile setters or architects specify white grout when a colored grout actually makes the colored tile look better.

It is very difficult, if not impossible, to make a dark grout appear lighter. Keep in mind that grout stains are not paints. In fact, you would never want to apply a paint to grout as they are films and will peel over time. Grout stains penetrate into the grout and carry the color pigments with them. Some stay at the surface so you can see the new color. But never will enough light pigments stay at the surface to mask a dark colored grout.