Black lines may indeed appear on your eavestroughs. While it is perfectly normal, it is in no way caused by Alu-Rex products. It is the result of accumulated dirt that drips down the front of rain gutters.

What causes these black lines on the eavestroughs?

Dirt, dust, tar from the roof, and pollutants deposited end up exposed as water from rain fall drips down the front of eavestroughs. Special cleaning products are required for these black lines to be removed.

Certain Alu-Rex products come with the Dura-Clean technology. The roll-back edge offers efficient protection and leads dirty water directly down the gutter and into the soil rather than letting it drip down the front side of the eavestrough. Ask your installer about these specific models that help prevent black lines from appearing.