EG+Hollow section preparation

I'm preparing to filled some hollow sections with EG. The inside of the hollow section is not greasy to the touch but there is a with a black substance that is powdery to the touch. Just like when we touch the side of a exhaust pipe.

I tried removing that substance with some turpentine soaked rags attached to one end of a hollow bar which worked okay for areas near ends of the hollow sections. But cleaning the entire inside of the hollow section is a real pain as it is difficult to reach all the areas inside with sufficient pressure to remove the substance.

Will that black powder substance prevent the EG from adhering properly to the hollow section?

Steel hollow sections?

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Originally Posted by pippin88

Steel hollow sections?

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Yes. S275 mild steel to be exact.

But cleaning the entire inside of the hollow section chinese buffet near me is a real pain as it is difficult to reach all the areas inside with sufficient pressure to remove the substance.

Its sounds like its a mill scale and people have used acid and vinegar and at least several other options to remove the scale...I was concerned with the same mill scale and what to use so I reached out to a welding forum and it was suggested to thy this...https://www.amazon.com/75-Pure-Vineg...p_0_10_t...its a 75% concentrate of vinegar in which you add water and get the job done...With all aside I bought 2 containers to use however I have not gotten around to using it yet but am expecting positive results...
best of luck and you are right to be concerned with this if you are filling up with resin or concrete...It will perhaps not all but enough will break down and break away from the metal surface...
Paul