Concealed (also known as “hidden” or “invisible”) zippers are coil zippers where you cannot see the elements because they are behind the tape. Normally, all that is seen is the slider. You might see this zipper in bags, pockets, formal wear, and other garments where a hidden seam is preferred.
Reverse Use Coil Zippers
Reverse use coil zippers are zippers where the coil is on the inside, creating a smooth finish on the outside.
The zipper chain is the same for standard or reverse use coil. The slider is what creates the reverse look. This type of zipper is not meant to create a hidden seam, but instead to create the illusion that the zipper elements are pulled together tightly.
This zipper comes in many sizes with many uses, such as a coated zipper that helps repel water. This zipper is used in bags, pockets, jackets, or where the water repellent function is desired.
Proper Use of YKK® CONCEAL® Zipper
CONCEAL® zippers may be used for tight-fitting clothing such as a dress. Zippers are usually closed with both stringers pulled closely, elements going into the slider and engaging with the other counterpart. For tight-fitting clothes, especially at tighter parts such as the waist, pulling both stringers closely to close the zipper may be difficult and sometimes the slider is closed forcefully even though the stringers aren’t pulled into position. In this situation, elements may go into the slider at an improper angle, and consequently get engaged with less area. This improperly engaged chain could burst with little force.
Make sure to pull closely together both sides of the garment before zipping up the garment. Attaching a hook & eye fastener at the top stops could reduce load against closed zipper chain.
Sewing of YKK® CONCEAL® Zipper
The CONCEAL® zipper is often sewn to the garment fabric at the line very close to, or even inside the folding line of the zipper tape in order to better hide the zipper. This sewing style could easily cause the chain to burst when the garment is worn.
In addition, when the zipper is sewn on thick fabric or at fabric joint, the zipper stringer / elements could get
turned up due to the nature of thick or folded fabric as shown in below diagram.
In this situation, it is harder to make sure the elements are aligned properly before entering the slider and slider movement could become more difficult. Forced pulling of the slider in this situation could easily cause mis-engagement of the elements and result in the chain bursting.
When sewing CONCEAL® zippers onto fabric, please sew outside the tape folding line, keeping the element vertical in order to give enough flexibility to zipper tape.
YKK Presser Foot for CONCEAL® zipper
Using YKK’s special presser foot for CONCEAL® zipper is strongly recommended as it can easily guide the needle to the proper sewing position.
Contact your YKK sales representative for more details about these zippers.