What are Reappearing Stains on Your Carpet?
There are several layers to your indoor installed residential carpeting: the carpet pile, the backing (2 backings, actually – the primary and the secondary), the padding, and the subfloor. When a spill occurs, gravity pulls the spill down through the carpet fibers where it may eventually soak down into the carpet backing, then the padding, and, given enough moisture, even the subfloor.
On some residential and many commercial carpet installs, the carpet is glued down directly to the concrete subsurface without a pad. Wicking also occurs in these installations from a collection of contaminants in the backing and subfloor.
Why Do Reappearing Stains Happen?
What is happening is that the left-over contamination below the area that is cleaned moves up to the surface as it dries. Carpeting always dries from the bottom up. So if you have residual contamination (such as a big urine spot) in your backing, pad, or subfloor, there’s a good chance that eventually the residue is going to wick its way up to the surface of the carpeting. Wicking often occurs with oil-based spills like coffee, cooking oil, salad dressing, etc., but can also occur if there is a big liquid area such as urine.
Coffee Stains: A Common Reappearing Stain
You’ve spilled your morning coffee and you blot it up the best you can, use a stain cleaner like Stain Fu, and dry the area with a fan, only to see the reappearing stains show back up.
Coffee can be tough to remove because of the chemical compound and oils of the coffee bean, the high temperature of the beverage, and added substances to the drink like cream and sugar.
Coffee contains a naturally occurring compound called “tannins” which acts as a vegetable dye. Tannin is the compound responsible for that bitter or dry taste in coffee, tea, and red wine. Tannins also have the tendency to wick back up into the top of the carpeting as it dries, even after seemingly successfully removing the coffee spill. So you may clean up the spill several times from the top side only to have the coffee stain reappear. Anytime you re-wet the top side of the carpeting, you expedite the wicking process. As much as you may try to not get the backing wet, it may get damp enough to wick the tannin residue from the bottom to the top.
How Do I Know it’s Wicking?
One way to find out if it's wicking is to inspect the cleaned spot after drying. Look at the fibers themselves. If the top third of the fiber is affected but the bottom third looks just fine, then that tells you that it is wicking.
How Do I Prevent Wicking?
Since the best way to prevent wicking is to make sure that the pad (and perhaps subfloor as well) is clear of contamination, we recommend the “weighted towel method”. This method allows the spot to “wick” and absorbs into the towels on top, instead of your carpet. Here is how to do it:
- Treat the area with Stain Fu
- Agitate the spot- We recommend using a metal spoon handle
- Stack a few white terry towels (or colorfast towels) and put something heavy on top of the towels such as a heavy book, weight plate, or a brick.
- Check the spot and towels in a few hours. The spot will wick up into the towels as it dries. Repeat if necessary.
Weighted Towel Method Example
- Don't rub or scrub the spot – agitate using a metal spoon handle. Using plastic spoons can distort certain carpet fibers.
- Make sure you use white terry towels, or colorfast towels, to prevent any risk of color transfer.
- Also be aware that whatever heavy object you use to weigh down the towels may get damaged by humidity or moisture wicking into it, which is why we recommend using a brick or rubber-coated weightlifting plate, if possible.
Reappearing stains can be annoying, but luckily they can be removed with the right cleaning technique. Let us know if you tried our methods for cleaning reappearing stains from your carpet!
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