How to solve the problem of spandex white exposure

The white or semi-transparent spandex can not be easily dyed by the continuous acid dyeing process,  for black or dark color elastic made of nylon spandex, without special treatment, the spandex white exposure will negativelly affect the total dyeing results.

We have two methods to solve this problem.
Method 1: use special dyeing agent / additive to make spandex dyeable without damage its elasticity.
Method 2: cover the spandex with nylon yarn before knitting or weaving, so the dyeable nylon yarn will cover the white spandex after being continuously piece dyed.

Pay special attention here, basically the elastic factory like to make the openwork knitted elastic by bare spandex instead of by covered spandex, you can ask them to use covered spandex if you mind the spandex white exposure after the elastic being piece dyed.