Six Nifty Lamination Tips
March 2017 Issue
After fitting a patient with a new prosthesis, do people say to him or her, "Hey, that leg is awesome. Where did you get it?" Custom laminations are definitely the way to get those kinds of comments. Here are a few tips to make your laminations easier.
Tips to Save Time
Remember all those liner tops that were cut off for final fittings? In my article, "The 'New' Pelite Liner: The Duralite Liner" (The O&P EDGE, November 2015), I mentioned that they can be used as toppers, instead of wrapping the check socket with plaster rolls, when pouring plaster into it. If you have an extremely large socket to pour, you can take two old sealing sleeves and cut each one lengthwise. This will leave you with two sheets of rubber. Using a flatbed sewing machine, loosen the presser foot tension until the foot tilts up a bit. This will allow you to feed the gel through without it bunching. With the gel of one sheet touching the gel of the other sheet, sew the two sheets together down the long edge of one side, as if you were making a large sealing sleeve. Wrap the gel sheet around the socket, and pinch it so it tapers from the ramus region and has a smaller opening at the top to prevent the cast from holding too much plaster. Draw a line on the sheet where to stitch it so it will close around the socket. Then stitch the two sheets together, with the gel touching along the marked line. This will be tight enough to prevent leaks. Now pull the stitched-together sleeve over the socket and pour plaster (Figure 1). This will save you time and plaster rolls, and the gel sleeve is reusable. Keep a couple of each size of liner segments at your plaster station.
You don't have to wait for your PVA bag to soak in a towel before it is ready to laminate. Fill your sink with cold water, open the large side of the bag, and dunk it quickly, using one hand to make sure that the entire outside of the bag is submerged (Figure 2). Remove the bag from the water and shake it for about 30 seconds to remove excess water. Pull the bag over the mold and use a clean towel to dry the outside until you can grip it and pull it the rest of the way down. I have laminated hundreds of sockets this way and it works great. If you are doing a two or three-stage lamination, this could save you 20-30 minutes.
Tips to Make It Look Good
To gain exposure for your company branding, you can add your logo to sockets. First, cut the logo off of a company business card to put under the stockinette. Once the cast is prepped for lamination, whether you are using a cast sealer or a PVA bag, pull a nylon stockinette over it, but don't tie it off. Make sure the logo is facing in and upside down so when you right the socket it is facing the correct way. I usually put it on the posterior region about an inch below the shelf if I'm making a transtibial socket, and on the lateral wall about four inches from the brim on a transfemoral socket. I have used acrylic resin with and without pigment, and E-R Resin, with good results (Figure 3). The pigment covers the logo a bit, but it is still visible.
When doing a cosmetic lamination with fabric your patient brought in, how you pre-position it on the cast is important to achieve a great looking socket. I usually keep the seam on the posterior side of transtibial sockets, and on the medial side of transfemoral sockets. This positioning allows for disruptions in the pattern to be hidden from view on transfemoral sockets, or for it to be made into a symmetrical design, if possible. I don't usually stitch fabric together for laminations unless it adds character to the design. For example, once I made a blue jean leg and I stitched the medial side to where it conformed to the socket and I kept the iconic stitching on the lateral side. Instead of stitching, I typically use 77 spray adhesive to glue the fabric down. Don't use too much adhesive as it won't allow the resin to penetrate, and don't spray too close to the fabric or it will deposit lumps of glue on the fabric that will leave spots on the lamination. Try to lay the fabric so you cannot tell where the seam is (Figure 4). If it is a repeating pattern, you can cut around some of the repeats to make it flow better.
Tips to Prevent Mistakes
Have you ever pulled your lamination dummy off only to find that the resin didn't impregnate past the carbon fiber in the middle? It could be because of how you tie in your layers. If you tie all of your layers in too tight, the resin has no way to get through. I made a core dummy that goes in the center of my laminations to prevent this. The core dummy can also be slipped over the post on a lamination dummy. Everyone does layups differently, but if you tie your layers a bit looser and stagger them, they will lay flatter and give the resin more access to the center. The core dummy spaces the layers away from the center so the resin can pool there. It can also be temporarily glued into place on the center of a puck or similar distal attachment (Figure 5). Once all the layers are tied in, remove the core and put on the cap.
We all try to prevent mistakes, but sometimes they happen. If you ordered a new type of lock and forgot to order the lamination dummy, use the instructions from "A Metal Lathe in an O&P Lab?" (The O&P EDGE, February 2015) to make a lamination dummy for a lock/dummy with a fourhole pattern. Once you have the layers tied around the core and you remove the core, you can use a scratch awl or an ice pick to find the holes and open them. Then use a soldering iron to melt through some of the excess to make threading the bolts into the lock/ dummy easier. Use the plate you made for your cap and thread the bolts in. The fabric threads can make it difficult to get through, but it can be done. Put some playdough or silicone putty in the bolt holes and tape off the top of the plate. If you made a center hole in your plate, leave the hole open so the resin can pass into the hole you made with the tie core (Figure 6). Laminate as usual.
I hope you find these tips helpful. If you have any questions, feel free to contact me.
Travis Petersen, BOCP, COA, works at A.O.P. Orthotics and Prosthetics, Fayetteville, North Carolina, as a practitioner and clinic manager. He has also worked as a practitioner and technician for companies in Missouri. He can be contacted at .