Typically, testing for brake fluid contamination is done at the master cylinder reservoir for obvious reasons. For moisture, it's probably the best place since air bubbles rise and the reservoir is located at the high point of the brake system. So you're getting a sample of the worst moisture condition, a good test.
And copper test strips are also dipped in the reservoir. But I'm thinking a better place would be at the caliper as the low point of the system where particle contamination is more likely to accumulate. Testing at the reservoir, while more convenient, is understating any copper contamination that may be much worse at the components lower in the system.
So I'm very curious to ask if anyone has actually compared a copper test strip at their reservoir with a second test strip at their caliper, perhaps when bleeding the brakes and some expelled fluid was handy?
And copper test strips are also dipped in the reservoir. But I'm thinking a better place would be at the caliper as the low point of the system where particle contamination is more likely to accumulate. Testing at the reservoir, while more convenient, is understating any copper contamination that may be much worse at the components lower in the system.
So I'm very curious to ask if anyone has actually compared a copper test strip at their reservoir with a second test strip at their caliper, perhaps when bleeding the brakes and some expelled fluid was handy?