Poultices on natural stone tiles: Are they safe to use on pavers?
The first piece of advice the internet gives you about stains on your natural stone is to use poultices. They, however, do not tell you what they are. This can be confusing especially if you have recently installed pavers.
A poultice is a chemical mixture that contains a liquid cleaner, which is mixed with a color-neutral absorbent material to create a paste-like stain remover. The end result has the consistency of oatmeal and can be used safely on natural stone.
This is not to be confused with the healing poultice which is used to treat wounds.
What do poultices do?
Poultices have one job, to draw out the stain from the tile and leave it looking new. This is done over some time, with the length depending on the type of stain. The poultice is spread over the stain and covered with a waterproof material such as plastic. The paste is spread at a thickness of between ¼ and ½ inch, to allow for enough of the absorbent component per square inch. Most poultices require that you keep the area covered for between 24 and 48 hours. Some stubborn stains such as wine, coffee, and pet urine require you to use the poultice more than once. Pet urine, for instance, will cause a combination of staining and bad odor, which will not come off in one application.
When dealing with natural stone, it is important to take note of the ingredients used in your poultice. Using materials that have acidic or basic properties opens the tiles up to a form of damage called etching. The acidic or basic ingredient will eat the surface of the tile and leave it looking unpleasant. Most recommended poultices will include fuller’s earth, powdered chalk, diatomaceous soil, molding plaster, talc, whiting, or kaolin.
It is important to note that you should not use iron-type clay, or even whiting, with an acidic cleaner. This is because the acid will counteract the effects of the poultice and render the application useless.
What should you know about poultices?
The internet has a lot of advice concerning different types of poultices, especially homemade ones, and how to use them. You will even get instructions on how to make one from scratch. Here are some of the things you need to know about poultices that are specific to pavers:
- Internet poultice recipes are dangerous. Most of them advise using components that could cause damage to your paver if used incorrectly. To begin with, you need a specific poultice to deal with a particular type of stain. This means the meticulous measurement of the ingredients, and since most recipes do not state the measurements, it is possible to have too much of one and ruin your tiles.
- Some poultice recipes that are touted to work in natural stone were designed for concrete. Since concrete is man-made from aggregate and cement, it reacts differently towards certain cleaning materials in comparison to granite or slate for instance. Do not trust any recipe that incorporates hydrogen peroxide or muriatic acid in the treatment of granite and bluestone respectively. The peroxide will cause etching in the granite. The muriatic acid, even when used to clean the grouting, will cause the stone to turn an unappealing yellow shade. This is because the acid will oxidize some of the metal elements in the stone, causing “rust”. You should also stay away from any directions that suggest using vinegar.
- Always try the poultice out on a small patch first for at least 24 hours. This test run is important if you do not want to ruin your pavers. Any adverse effects of the stain will be seen on the stone first. Pick a part of your paving that is constantly hidden by furniture to try it on.
- If the stain is oil-based and recent, try using dish soap first. Make a concentrated solution from the dish soap and warm water, then use it to cover the stain and allow it to seep into the stone. Wipe it down with a clean cloth and repeat until the stain is gone. If the stain persists, call a paving professional!
The dos and don’ts of cleaning pavers
Most of the mistakes people make when cleaning pavers are out of ignorance. To help understand how to treat natural stone, here are 5 things to keep in mind:
- DO NOT CLEANERS THAT CONTAIN AN ACID OR A BASE. This cannot be stated enough times. It is the easiest way to cause etching in your tiles, which will cost you a bundle to fix. This is because repairing etching damage will require specialized equipment, and for best results, extensive experience working with natural stone.
- Wipe down any spills as soon as they occur. This will minimize the amount of time the irritant is in contact with the stone, and reduce the chances that a stain will be permanent. Oils and smoke, for instance, will require time before the stain is permanent.
- Hydrogen peroxide is the enemy of most natural stone tiles. It does, however, work on unsealed true granite. On marble or metamorphosed granite, the effects are devastating. When in doubt, one of the ways to verify the stone to check for veins, since true granite does not have veins.
- Ammonia and vinegar will cause damage to your stone. Vinegar being acidic, will dissolve sensitive pavers such as marble and travertine. It will also dissolve the grouting cement and leave your pavers loose. Ammonia, on the other hand, will burn off the polish on travertine. It also poses a danger, since when mixed with bleach, it will give off a lethal gas.
- Seal your pavers. Using a quality sealer on your pavers is a great way to avoid stains. The sealer creates a protective layer around the stone, reducing its absorption capabilities. Here is a guide on the importance of sealing pavers.
Remember, when doubt, always go with a trusted and verified professional.