Recurring Stains

Life as a carpet cleaning technician would be so much easier if we did not have to worry about recurring stains. This is a very common situation that happens and sometimes can present some frustrating experiences for the textile technician.

In order to properly deal with this situation, we first have to understand what makes up a recurring stain. Typically these stains are easily removed with industry standard cleaning practices, but will reappear either when the carpet dries (usually the morning after) or will start to come back several days after cleaning. The stain that usually takes longer to reappear typically comes back in a darker shade and is likely to get bigger as time goes along.

We also have to understand the different types of carpet fibres and how they affect the stain. The commercial carpet market is typically split 50/50 between nylon and polypropylene (olefin). These carpet fibers react differently with materials that are spilled on them.

If we were to take these two carpet samples, one nylon, one polypropylene and leave them in a room at normal temperatures with 30% relative humidity, the nylon sample will absorb -4% moisture while the polypropylene will absorb only .1%.

While this may not seem like a big difference, lets examine what happens if we spill a cup of coffee on both types of carpets. We know that the coffee spot will fall not only on the visible part of the carpet, it will also go underneath the carpet. In the case of olefin, what we ware really seeing is .1% of the stain, with the other 99.9% still underneath the carpet. When we clean the carpet (using any system that uses moisture), we will re-wet the stain and the dried coffee reservoir will now wick up to the top as the carpet dries. We have seen cases where you can clean carpet 15 or 20 times and the stain will still come back. This scenario will also happen with nylon carpet, however, it is the polypropylene one that seems to cause more of a problem.

The most frustrating part of all this is that the spot itself cleans very easily and so your staff is justifiably proud of the job they do. So here are some tips that will make your job easier.

  • Recognize the fact that if the spot returns one cleaning, it will probably come back again.
  • DON'T OVER WET! If you use extraction cleaning, spray a light mist over the spot and then extract. If the fibers get too wet then the moisture will go down to the bottom of the carpet and will re-wet the dried spot.
  • Consider bonnet cleaning the area. Spray a properly formulated bonnet solution over the affected area and bonnet clean using a low speed floor machine. While this will not remove all of the staining material it will keep it hidden underneath where we can't see it. This is a very effective way to keep those stains from coming back. This same process can be repeated using weighted towels. (Put a heavy object over the towels to help absorb the staining material.
  • Take a spotting agent and continue spotting the spot until it does not return. This process may have to be repeated many times before the entire spot is removed.

If the stains reappear after several days you can repeat the same procedures, however, bear in mind that you are probably dealing with a different kind of stain. More than likely it is either an oily based or sugar based material. If it is an oily base material you may have to use a solvent based product to solubilize the material. (commonly referred to as a P.O.G.) If you do use this type of material, then it is imperative that you use a dry cleaning solevent to flush the P.O.G. out. These materials do not flush out with water. Typically if they are not flushed out properly, when they reappear they will usually be black in colour. The reason that they come back like this is that they were never flushed out properly in the first place.