Most Dry-Cleaners today do alterations, even though we do not have any issues with their cleaning, however we do have issues with their alterations.
Tailors in Europe may use linen threads. American tailors do not generally use linen thread.
Therefore in America, we are not concerned that tailors or cleaners are using linen thread.
The concern today is that a tailor or a seamstress may add a shoulder pad or a fabric to a garment and may thereby create Shatnez. If the garment was woolen, and the added fabric used to alter the garment is linen or vice versa, the garment becomes forbidden to wear as Kilayim.
To read the entire article, please click on the hyperlink to the right; 14 Jan Alterations
To contact shatnez expert Rabbi Eliyahu Neiman directly, please email shatnezlabint@gmail.com