Is dark brown metal under paint copper?
Scratching away paint on a pipe often reveals a dark brown color instead of a shiny finish, leaving people unsure if the metal underneath is actually copper. This ambiguity makes it difficult to determine the actual pipe material or whether connections need to be cut out.
What the numbers show
Counted from the threads quoted below. How we count
- The most recent one is from October 2026.
- This comes up 16.1× more often in r/Plumbing than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
Is dark brown metal under paint copper?
- 1Scraping away paint to check the colorDid this help you?
- 2Sanding the oxidation to reveal shiny metal underneathDid this help you?
- 3Checking if the pipe can be dented with a fingernail or crushed by handDid this help you?
- 4Leaving the connection alone if it is not leakingDid this help you?
- 5Consulting a licensed plumberDid this help you?
- 6Replacing the connection using a proper transition donut or gasket with lead and oakum, or using a ferncoDid this help you?
- 7guessing the pipe material or compatibility based on visual appearanceDid this help you?
- 8consulting online forums to identify unknown pipe typesDid this help you?
- 9Replace a 90-degree elbow further up the pipe with a tee and add an auto vent at the top instead of cutting the unknown pipe.Did this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“Is this an approved connection or should I cut out the hub and fernco?”source ↗
“I'm trying to replace the old shutoff valve since it was leaking, bought a compression valve meant for copper from Lowe's and came home to see this. Looks like a plastic tube with a metal insert.”source ↗
“I scratched away the paint in the second pic and it was this brown colour under.”source ↗
“Okay thanks but shouldn’t it be shiny if it’s copper this is like a dark brown”source ↗
“Nah it’s hard like construction adhesive!”source ↗
“I stared at this for a solid minute trying to figure out what I'm even looking at.”source ↗
Where this came up
People with this problem also raised
- 15What is this random dripping exterior pipe on my house?
- 3Which plumbing pipe material is actually best for a whole house?
- 16What is the fluffy stuff in my attic and is it safe?
- 4How to tell if crusty residue on a basement pipe is a sewage leak
- 19Metal flakes in engine oil after buying a used car
- 26How to identify unknown plumbing parts in a building