A Quick, Easy Way to Save Time and Money: Sealing Nylon Vacuum Socks

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By Jack Pranzarone CP, LP

I would like to share with you a discovery I made a few months ago.

Heat Wheel Sealer
Heat Wheel Sealer

Having begun my career over 20 years ago as a technician, I still have a slight bend toward the technical side of the house. Being extremely picky about quality work and craftsmanship (they say I'm anal), and wanting the best for my patients, I still do a lot of my own tech work. With an extremely busy practice, time is always an issue. Consequently I am always searching for new techniques that work and save time--both technical and clinical. It is the little things that we do many times a day that cumulatively consume so much time, and it is here that I have found a neat little trick that can save time and money.

This all started by sealing PVA bags. Many of you can remember the way we capped the end of a mold with a PVA sheet, then a bag to seal it before lamination. For several years I did it this way. Then on a trip to Minneapolis, Minnesota, Steve Rebhuhn of Otto Bock showed me his PVA bag-sealing trick. It involved the use of a SealLine ® brand special sealing iron that included an electrically heated steel wheel that was simply rolled on the wet PVA bag to seal it. You could conform the PVA bag to any shape mold by just rolling a different sized arc. We loved this thing. And it worked for nearly 15 years before we wore it out. But when it gave up the ghost, we could not find another one like it anywhere. After looking for nearly two years, I found one at Heatsealers.net. The company offers a complete line of sealing devices, many of which may have O&P applications.

PVA Bag Sealer Does the Trick

12-in. Impulse Sealer
12-in. Impulse Sealer

Enter Randy Roberts, CPO, of the Pensacola branch of Hanger Prosthetics & Orthotics. He showed me his version of a PVA bag sealer. This was a neat little 12-in. impulse sealer that is an affordable, easy-to-use device that makes watertight seals on polyethylene bags, PVA bags, or any thin weld-able plastic material. What is neat is that the element heats only while sealing. These are available from nearly any of the mail order hardware outlets, including Harbor Freight; item # 43476-2VGA, Quill office supplies; item # 901-SPB12, and online at Heatsealers.net. This thing will seal a wet or dry PVA bag in a straight line. It is foolproof and quick. Turning the bag at an angle and clipping the corners with the sealer produces a nice seam for rounded objects. This tool does a wonderful job on PVA bags, but just wait until you see what it can do with stockinet and nylon vacuum hose.

Okay here's my part in this story. We buy our air wick nylon vacuum socks from SPS. They come without toes. Both sides of the house use these for vacuum forming both in thermoplastics and in laminations.

Problem is we always have to deal with the open end of the sock. We usually tie it off, fold it under, melt it together with a lighter, or sew it shut. We do whatever is needed to produce the best seam needed for the specific project at hand.

Preparing to seal nylon vacuum hose
Preparing to seal nylon vacuum hose

Well, the other day I needed to use one of these nylons on a BK lamination. I always want as smooth a seam as possible as it will sometimes show in the finished product. Normally I would tie it off with a thin thread and cut off the excess, then drill a hole in the mold and insert the knot in the hole. When done correctly, this produces a very nice finished smooth distal end. But it takes some time.

Sealer Great for Other Applications

Then the thought hit me...nylon melts! I put the nylon in the sealer and lowered the handle. Three seconds later...Voila... a perfect seam!

This worked so well it was amazing. I did it again and again--perfect each time.

The sealer works just as well with finish nylon stockinet too.

Sealed nylon vacuum hose
Sealed nylon vacuum hose

Then it occurred to me that Nyglass ® should work as well. I put it in the sealer--and again a perfect seam. Due to the increased thickness it took three presses in about ten seconds to get it melted all the way through, but it worked great.

Now in our practice we all are using this technique to seal the nylons we use everyday. We also seal the Nyglass we use in our lamination lay-ups. This produces a superior-looking finished product and saves weight by not having so much fabric at the distal end to soak up resin.

  • Buy the nylons with no toes, and save money.
  • Seal the nylons quickly and easily and save time.
  • This also works exceptionally well sealing the nylons we use on our thumb spica molds. It easily makes a thumb and index finger seam that conforms to the mold much better and prevents the nylon from bridging the gap.
Trimmed nylon vacuum hose with seam
Trimmed nylon vacuum hose with seam

Seamed PVA bag with clipped corners
Seamed PVA bag with clipped corners



These impulse sealers range in price from $29 to $129, depending on where you buy them. I have examined the lowest- and highest-priced units in the 12-in. size and cannot find any significant difference other than price, so go for the least expensive unit. It is my opinion that the 12-in. model will be all that is needed for a busy O&P facility.

Seamed Nyglass over mold
Seamed Nyglass over mold

Mold with seamed nylon and PVA bag
Mold with seamed nylon and PVA bag



We initially bought this sealer to use for sealing our PVA bags for laminations, but now it is used many more times a day for seaming the nylons and Nyglass products used in other methods of fabrication.

I'm sure that you will find other uses for this device as well.

Good Luck!

Jack Pranzarone, CP, is employed at Hanger Prosthetics & Orthotics Inc./Ft. Walton Orthopedic Inc., Fort Walton Beach, Florida.