On a winter day, you reach for a car door and feel a sharp zap. At a safety shoe factory, static can cause a much quieter problem. The sole passes the peel test. The conductive strip is in place. Yet the finished shoe gives a resistance reading above the buyer’s limit. More pairs of the same style are waiting to be packed. Should you change the glue, move the glue line, or adjust the way the line runs? Each choice could affect the ship date.

Start with the way the shoe is built. In some shoes, the end of the strip must touch another part directly. The glue holds the strip in place. In other shoes, the current must pass through the glue between two parts. In that case, the resistance of the glue layer matters too. Two cutting patterns may look much the same yet call for glue in different places. A photo of the finished shoe gives a supplier little to go on when a buyer asks, “Which glue will pass?”

Before approving a safety shoe sample, ask three questions.Where does the current flow? Which parts need a firm bond? How will the buyer test the finished shoe? The brand sets the target resistance range and the test conditions. If the buyer specifies ISO 20344, confirm which edition and test method to use before making samples. The factory marks the overlap on a drawing that shows the shoe in cross section. The buyer can then ask for samples. This guide covers two types of shoe glue, solvent-based and water-based. Both can have a place in an antistatic shoe. If a joint must carry current, test the chosen glue on the materials used in that shoe.

1. Solvent-Based Shoe Glue: What Should You Check First on an Existing Line?

Can you keep your current glue? Check the end of the strip

Suppose the work sheet says, “Glue the conductive strip to the midsole.” The sample maker knows to leave the tip free so it can touch the sole material. A worker on the line may brush glue along the whole strip. Both strips lie flat. Open the shoes and the difference is clear. One tip touches the sole material. The other has a film of glue at that spot.

Start with two small sets of samples. Use the same batch of strips, the same sole material, and the glue already in use. Make the first set the way the line does it now. For the second, use the drawing to mark where to apply glue and where to leave the strip bare. Keep the overlap length and press settings the same. Check whether the strips moved, then compare the resistance at each joint. If leaving the contact area bare brings the reading closer to target, update the glue template. Add a photo with measurements to the work sheet. The buyer can keep the materials that passed, and the factory knows which workers need training.

Even with glue in the right place, the strip can slip as the press closes. Trace the tip before bonding. After pressing, open the sample and measure how much of the tip still touches the intended area. This simple check tells you whether glue crossed the line or the strip moved under pressure.

If current must pass through the glue, how can you test a new glue?

Some designs call for a full bond between two parts that carry current. With no separate point where those parts touch, a conductive glue is worth testing. Send the supplier samples of both materials, details of how you prepare each surface, and a drawing of the overlap. A short piece of strip alone gives the supplier too little to recreate the joint.

Make one set of test pieces with the current glue and one with the new glue. Use the same shoe materials, overlap size, and test conditions. Follow each glue’s own instructions for surface prep, drying, and heat activation. Record what you do. Place one test contact on each side of the bond. Keep the bare edges of the materials apart. If they touch, current can flow around the glue and give a misleading reading. Foil can help show how this works. For glue selection, use the buyer’s actual shoe materials. For a method used to check resistance in footwear parts, see SATRA TM240.

HELEY 286 conductive PU glue is one option to test for this type of joint. HELEY’s product notes call for a primer and recommend heating the glue at 50–70°C for 3–5 minutes to activate it. The matching hardener helps the bond resist heat, damage from moisture over time (hydrolysis), and aging. Before making samples, ask the HELEY technical team which primer to use, how much hardener to mix in, and how to cure the bond. The available notes do not say whether 286 is solvent-based or water-based. It appears here as an example of how to test a joint that carries current. Buyers should check the official data sheet before listing it under either type.

The test joint performs better. How much of the line needs to change?

A new glue may give a better reading on the test piece, yet the strip may curl up once it is in place. Run a trial at normal line speed. Have workers pick up, fit, and move each part as usual. Record the time from fitting the strip to pressing it. Check whether the tip lifts while it waits. If a worker has to hold every strip down by hand to keep it in place, the lab result alone is too little to base a bulk quote on.

What if the joint gives steady readings and the strip stays in place, yet the whole shoe still falls outside the target range? Follow the current path through that same shoe. Check the other parts and the places where they touch. Adding more glue at this stage changes the film thickness, the cost, and the way workers apply it. That makes the cause harder to trace. On an existing solvent-based line, record the exact shoe style, joint, and set of materials that passed. Other stations can keep using the bonding process each one needs.

2. Water-Based Shoe Glue: What Should You Test Before Winter Production?

What does the brand’s water-based requirement cover?

“We need water-based glue for this shoe” can mean two different things on a purchase order. One brand may require water-based glue at just one step. Another may also set rules for the primer and hardener. Check the scope before making samples. Even if a sample shoe passes, a late change to the primer or hardener may mean the factory has to check the process again.

A buyer could write, “We need to bond a conductive strip to the midsole. Current must pass through the area marked on the drawing. We have included both materials used on our line, our line speed, and the brand’s material requirements. Please suggest a water-based glue and list the other products it needs. Please include drying instructions and the conditions you used for tests on similar materials.”

If only the middle of the strip needs glue, mark the contact area at the tip separately. The supplier can then address the right question. Does the fresh bond hold the strip in place, or does the glue layer need to carry current? Buyers can use the same brief to compare quotes.

What can two sets of Safety Shoe Samples Tell You in Winter？

Drying time is easy to overlook when a water-based glue moves from the sample room to the line. In the sample room, the maker can check the glue film and wait a few more minutes before pressing. On the line, the equipment and line speed set the time each shoe spends in the dryer. Those extra minutes may be hard to fit into the schedule. HELEY’s guide to switching a shoe line to water-based glue explains what to check during the change.

Take the first set of safety shoe samples at the start of the morning shift.Record the room temperature and humidity, the state of the equipment, the time in the dryer, and the amount of glue used. Take the second set once the equipment is running steadily at the planned speed. Record the same details. Use shoe materials from the same batch and the same water-based glue for both sets. Cure and test them under the same conditions. Check the strip position, the bond, and the resistance of the whole shoe. The two sets can show where results differ. To find the cause, change just one condition in the next trial.

For example, both sets may have firm bonds, yet the strip shifts only in shoes made at full speed. First check how the parts move between stations and what holds the strip in place before pressing. Or the glue film may look right at low speed but fall outside the supplier’s drying requirements at full speed. Check the actual drying time, airflow, and amount of glue before changing the line speed. Use the water-based glue’s own instructions when setting up the trial. Heat settings from a solvent-based glue will tell you little about how this product dries on your line.

How can buyers work out the true cost per pair?

For a safety shoe order, the glue price per pail is only part of the cost. The cost of filling the order takes more work. During the trial, record how much glue, primer, and hardener the team takes from stock and how much it returns. Also record the hours used and the number of pairs that pass. To find the bonding material cost per pair that passes, divide the total cost of materials used in the batch by the number of pairs that pass. Include any glue or other bonding materials used to recoat a part or replace a strip. Count each amount once.

Work out the time needed as well. Take a sample order of 4,000 pairs. Suppose two processes meet the buyer’s requirements. One turns out 200 good pairs per hour, and the other turns out 160. The first needs 20 hours on one line. The second needs 25. Even if the second glue costs less per pail, can the line spare those extra five hours before the ship date? With both figures in the quote, the brand can see whether a switch calls for a change in the materials budget, the schedule, or both.

For either type of glue, keep one clear record of what passed. The factory keeps the approved sample shoes, the overlap drawing, and the line settings. The brand records the test method, the conditions used to prepare the shoes for testing, and the accepted range for whole-shoe resistance. It also decides whether the order calls for another resistance test after durability testing. The buyer lists the approved glue and all matching products on the order. If the sole material, strip, or supplier changes next time, the team knows which joint to check and has a sample for comparison.

If the sole holds firm but the finished shoe tests above the buyer’s limit, send HELEY the conductive strip, the sole materials on both sides of the joint, a photo with the glue area marked, and the buyer’s target resistance range when you ask for samples. Start with the joint that caused trouble in the shoe. The first trial can then answer a practical question. Should you move the glue line, hold the strip in place more securely, or test a conductive glue?