Anyone knows what this blob of orange fluid is? It looks thick and viscous, almost like secretion from some insect.

About 3 -- 4 years ago, I was painting the jack posts in our basement and noticed that a few of them had these fluid droplets surrounded by rust (just like in the picture below) on the surface. I cleaned them up and used the Rust-Oleum Rusty Metal Primer before painting. In a year or so, these began to reappear and now many of the posts have them. The fluid seems to dissolve the paint and cause the steel to rust.

Jack post

  • You have galvanic current inside that pipe that eats true it.
    – Traveler
    Oct 24, 2023 at 3:32
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    Calcium chloride used to be commonly used to accelerate the early strength of concrete. I can easily imagine that mass production of posts like yours would use calcium chloride to hasten production. With the post capped, I don't see any means for excess water from the concrete hydration to escape. I'll tenuously speculate that water plus calcium chloride are consuming the steel from the inside. I suppose I should have asked: Are these posts concrete filled?
    – popham
    Oct 24, 2023 at 3:51
  • What's going on at the base of the post? Is there moist soil or standing water that could climb the inside of the post by capillary action (in a thin layer between the concrete and the steel)?
    – popham
    Oct 24, 2023 at 3:59
  • @popham Not the first owner of the house, but I would assume that they are filled with concrete. The posts are connected into the concrete floor, and I don't know if the floor is weatherproofed from below. These blobs of fluid actually seem to usually appear initially from high up on the posts.
    – P. B.
    Oct 24, 2023 at 5:22
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    If you hit the post with something metal, do you get a ring or a thud? If it rings, it's hollow, if it thuds, it's been filled with concrete.
    – FreeMan
    Oct 24, 2023 at 13:46

2 Answers 2


The orange fluid is rusty water. The corrosion started inside the column and has finally eaten through to the column's visible side. Searching the internet for lally column oozing yields many instances very similar to yours. If the column is concrete filled, then I suspect that calcium chloride accelerator and water are causing the corrosion. If the column is hollow, then I suspect that moisture is moving through your foundation, into the post's cavity, and then condensing on the steel's inner surface.

The visible damage looks insufficient to require replacement, where hopefully somebody can rehab the existing columns.

  • They look more like surface rust at the moment (and my picture was taken on one of the worse regions). But it seems unusual that they wouldn't think of the corrosion potential of salt infused concrete in contact with steel. Or are the columns supposed to be insulated from the ground so what we have is really an improper installation?
    – P. B.
    Oct 30, 2023 at 4:41
  • @P. B., it's hard to anticipate anything besides flooding that would rust out steel in a controlled environment like that. I wouldn't expect the water to be available. And so much that the post literally weeps? My instinct on a fix would be breaking the capillary path from below, as I can't imagine that much water coming from elsewhere. Cut off maybe the bottom inch, install a steel base plate, and grout below that. Then punch some 3/4" or so holes in low stress areas so that the water can slowly diffuse out. Maybe run a dehumidifier first and see how much water comes out of the air every day.
    – popham
    Oct 30, 2023 at 5:13

What you see is most certainly rust.

It is a concern because it is compromising a component that is giving major support to that beam above it.

You should have consultations with a few contractors regarding adding support for the beam and removal of the existing column. The cause of the rust needs to be addressed. ( We cannot diagnose that here.) Then a plan to replace the column and prevent future issues must be spelled out. It may be something simple, like just a new column insulated from the concrete. Or something like groundwater under the basement slab.

I do not want to be an alarmist, but this is an issue that must be addressed by professionals and not diagnosed and have repair plans issued from well meaning but underinformed internet folks.

  • What kind of contractors are specialists for this type of problems? We are in a small town and I often had a hard time to find the right, well informed professionals here. Also to clarify, did you mean that the orange fluid blobs are just initial stages of rust formation?
    – P. B.
    Oct 24, 2023 at 13:14
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    You may need to go outside your small town to find a GC that specializes in home construction or major renovations. The orange blobs are an indication of both water and the oxidation that it causes in metal (rust). I say water, because it is not within normal expectations to have other fluids or something like bugs within a support column in a basement.
    – RMDman
    Oct 24, 2023 at 13:19
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    Unless you're a long way from a bigger city, contractors in big cities will usually come to smaller towns. Even in small towns, there are generally reputable builders. You may have to look out of town, but there will be someone, somewhere that your friends/neighbors/relatives will give a hearty recommendation to. Even in the more remote areas of the US West (where it can be quite some distance between small towns). Contractors there are going to expect to have to drive to get to jobs...
    – FreeMan
    Oct 24, 2023 at 13:49

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