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Oily substance on basement blocks

  1. Mar 8, 2016 #1
    I had some nice rainfall the past few days. I look in to basement and see a shimmer on several blocks. Looks like water but when I touch it and rub it between my fingers it's more like a chemical oil feel. Any ideas?

    ImageUploadedByPhysics Forums1457466234.083980.jpg
  2. jcsd
  3. Mar 8, 2016 #2

    I'm rooting for paint. Oil paint bleeding. Maybe someone will know better. :oldsmile:
  4. Mar 8, 2016 #3
    Try dabbing it with a piece of white paper. If it's oil, once it dries the oil will stay behind and make a stain. Might be useful to help identify what it actually is. The colour might also be indicative.
  5. Mar 8, 2016 #4


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    Gypsum "cooks" from blocks. Powdery?
  6. Mar 8, 2016 #5
    Silt maybe? This has happened to me in the past, the particulates in the silt were very fine, and combined with how cold the basement usually was it would usually feel like a viscous fluid when touching them.

    Does the basement smell earthy, like fresh dirt? It could also be mildew if that's the case, judging by the color on those blocks where they were wet.
  7. Mar 8, 2016 #6
    No oily

    I'm getting a basement guy to take a look next week.

    Not much, I have a humidifier running now
  8. Mar 8, 2016 #7
    It's not the side of the house that used to have the fuel oil barrel sitting outside of it at one time is it?
  9. Mar 8, 2016 #8
    No, street side
  10. Mar 8, 2016 #9
    I was wondering the same thing, there are many bitumen based waterproofing products on the market used on the exterior of foundations that could explain the oily residue also. There are many factors to consider such as age of foundation, type of building material used, possible groundwater contamination, it looks like some kind of water sealant was applied to the interior of the foundation wall so there may be a history of problems with seepage. You may want to consider having a sample of the residue tested chemically to see what your dealing with. (there is a lot of scary stuff in ground water depending on your location) I would also get several estimates/bids from reliable contractors and compare prices if your going to have a contractor do the sealing.
  11. Mar 8, 2016 #10
    Hah, this just reminded me of stories I've heard of old farmers and what they often did with their waste oil. Cheaper than roundup and worked just as well to keep the weeds down around the buildings...
  12. Mar 8, 2016 #11


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    It would be a good time to get a microscope and look at a sample.

    Could it be a slime mold, or otherwise, Latex-based paint?
  13. Mar 8, 2016 #12
    So many possibilities, some of them serious, some merely annoying. The testing idea is a very good idea especially since basements tend to collect contaminants.
  14. Mar 10, 2016 #13
  15. Mar 10, 2016 #14


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    Greg, did you check your TCP/IP settings yet? o0)
  16. Mar 11, 2016 #15
    Possibility. There's a reason "saw snot" is jargon for the slurry that comes off a water cooled diamond blade in concrete. Awful stuff. And it can indeed develop a soapy or oily feel on a surface. Dangerous when that surface is what you're standing on.
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