After a long search to find a factory that’s a good fit to make your product you are finally ready to press GO on these samples until your IP attorney advises you to have everyone who works on your product sign an NDA. At this point, your contractor may not want to, but why?
            An NDA (Non-Disclosure Agreement), also known as a confidentiality agreement, is meant to protect any type of confidential and proprietary information that is not publicly known.

Many of the new designers we work with ask us to sign an NDA, which my company and I gladly comply with; your info is safe with us!
But this subject can become tricky in development where parts of the process are contracted out to fabric vendors, sewing factories, etc. Generally, most contractors will not sign an NDA, but this is NOT because they don’t care for your designs.

Factory owners have no interest in voluntarily showing your products to other designers; they are in the business of serving you and keeping your business. Knowing how important your designs are, sharing them would hurt your business as well as their business, not to mention would result in a bad reputation.

The main reason they will not sign an NDA is because they really cannot control who will see your product while it’s at work.
Throughout the day designers, assistant designers, interns, and production managers are in and out of the factories to check on their own products. Inevitably, your samples might be sewn on a machine next to another company’s products and chances are a designer walking in to check on their designs will get a glimpse of your work as well. There is really nothing a factory owner can do to prevent people from seeing your fabric, prints, and designs as they all share the same space to iron, hang, and quality control.

Because factory owners cannot guarantee absolute protection, can you blame them for not wanting to take full responsibility of signing an NDA?

P.S That being said, with the rush and chaos of the fashion industry most people are too concerned with their own projects and deadlines to take the time to sift carefully through other designer’s garments. 

NOTE: The above is my personal opinion and since I'm not an attorney if you would like to get an informed and legal advice about your case please contact a fashion law attorney.