SFA: What's the Answer?

CNC Vacuum-Pod-Shaped Stains on All Marble


I'm wondering if anyone else has run into this issue. A few weeks back I started noticing yellowish stains on the surface of marble that has been run on one of my 2 CNCs. The stains are in the shape of the vacuum pod seals that were used on the particular pieces.

I am using about 50% CMS original pods and 50% ADI vacuum pods. The ADI pods have been in service for about 2 years with no issues. Yesterday I ran a marble vanity on a set of pods with all brand-new and cleaned seals, the same stains were present when I pulled the piece off of the machine. I believe this rules out the seals being an issue.

Right now I'm leaning more towards a water-quality issue. A few key components of our water-treatment systems are down so we are running a mixture of treated and city water right now. Just wondering if anyone has seen this before or has any suggestions that I haven't thought about yet.


Dan R.

SFA Member

If there were pod-shaped stains on the piece, how does that rule out seals? The seals were cleaned, my guess is not good enough.

Were the seals cleaned before or after they were on the pods? If after installed on the pods, how about the hidden sides of the seal?

How would water only stain around the seal?

Dan R.
Morris Granite
Morris, Ill.
815.228.7190 morrisgranite@sbcglobal.net


SFA Executive Director

I also recall a post saying NOT to use acetone to clean the rubber. What did you clean with?

Mike Dean, SFA
The Top Shop Inc.
London, Ontario
519.455.9400 x230

Joe Durfee

SFA Director

mikedean wrote:
I also recall a post saying NOT to use acetone to clean the rubber.


Look at the response from Larry.

Joe Durfee
Production Manager
American Floor Covering
Cell: (860) 338-9632
Team Motorboat


SFA Member

I would try running fresh water through everything and see if the problem solves itself.

I think if there are contaminates in your recycled water, they may be leaching into your marble around the seals.

Just a thought.
Lester Swick
Custom Marble & Granite
Butler, Pa.
908-418-5925 cell

Omni Cubed Larry

Friends Level Sponsor

Brembana4axis wrote:
..... that has been run on one of my 2 CNCs. ......

Put one of the pods from the machine that produced the stained stone on the other machine that didn't produce stains, and see if it behaves the same. If there is no stain, then it is a water problem (in the other machine). If it stains, then it is a pod problem.

You said you have some challenges with your water-treatment system. Are you running the same mixture of treated and city water through both machines? Why would one machine behave differently? Maybe answering that question will solve the mystery.

I had another thought. Black rubber cleaned with acetone will slowly break down and will usually leave black stains. Some chemicals in rubber compounds can leave yellowish stains when it reacts with other chemicals. I doubt it, but the seals could be reacting with some new chemical in the water.

Or, you cleaned the pods with something that the rubber didn't like. I have no idea what the ADI or CMS seals are made of. Or the stone has some different resin on it that is reacting with the rubber.

I'm not a chemist, but this stuff can be fascinating AND really weird sometimes. I hope you can get to the bottom of this quickly.

Larry Livingston
Omni Cubed Inc.
877.311.1976 office
530.748.3111 direct

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