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Using Our Adhesive for Inflatable Boat Repair

This page should give all the information necessary to perform effective repairs on many types of inflatable boats. We still recommend the use of contact cement on hypalon, but we do include how to interface it with our adhesive so that PVC parts can be applied to it.

The Main Topics on this Page


Technical Comment Before Reading This Material
The information on this page is very technical. Making repairs is not very hard if you remember a couple of simple rules.

Have patience. Let the glue cure.
Be aware of humidity. It is the enemy of a good job
Glue enough material to do test reactivation patches. Reactivation is the critical process. If you test your reactivation process, you can not fail.
Now anyone can do a patch, and you do not need a phd to read this material. Just get the general idea of how it works. We have never had to replace a patch done by someone who read these instructions.


UR1087 Glue and LA4009 Accelerator

WARNING: Use caution when working with this adhesive. Be careful with hot objects. Keep MEK and glue off of skin. Avoid breathing vapors. Use only in a well ventilated area and away from any open flame, including gas appliances equipped with pilot lights. In case of eye contact, wash eye with running water for 15 minutes, and call a physician. If ingested, call a poison control center. Give water or milk as a dilution agent. Glue is urethane based. Evaporative product (80%) is toluene and MEK. Accelerator contains POLYisocyanate

This glue is the most effective PVC glue on the market today. It requires some care and caution in it's use. Vinabond can be used for field repairs, but will reactivate with heat. If you understand the principals of heat transfer with this glue, we recommend it's use in the field.

The biggest problem that I see with repairs is the inability of the repair person to be patient. Granted that sometimes it is not possible and time schedules need to be met, but most of the time on really difficult repairs that are done in the shop, patience is a virtue that needs to be noticed. If you doing a really difficult repair, that needs to bond well and have good adhesion immediately, or if you are gluing to encapsulated Urethane material, try putting on two coats of glue, and then going to bed and putting on the third coat in the morning after reactivating it with damp MEK cloth. This gives the glue a chance to bond better to the coating without the chance of the glue pealing off of the PVC or Urethane, or the PVC or Urethane pealing off of the fabric. These coatings will get soft as a result of the adhesive attacking the coating chemically. This is because the evaporative product is usually a melting agent for the coating. That is how it adhesives work.

Gluing Neoprene and Hypalon
This glue works well on PVC Urethane and Neoprene. It works best on hypalon if it is interfaced with contact cement. We have had good success gluing Avon logos that are made out of PVC back on Avon Hypalon by putting contact cement on the Hypalon, and then putting a layer of this glue on top of that a day after. The toluene in this glue helps it to stick to the contact cement. In this way there is an interface of different glues that are sticking to each other.

Please note that we have had good success gluing directly to hypalon. However there is an age bonding process that must take place. For this reason, we recommend the interfacing of these adhesives.

Mixing Instructions
The accelerator container you received has the proper amount of catalyst for the amount of glue you received. We have found estimated proportions work just fine. A more precise measure 98 percent glue and 2 percent accelerator. We use a gram scale at the shop to measure, but we have done a few field repairs that are still working after 5 years, and these very instructions have helped novice repair people do their first successful field patches.

Pot life of the mixture is 8 hours. Do NOT mix more than you will be able to apply in 8 hours. Reactivation time is approximately 8 hours. Best results are obtained by applying the patch between the first and second hour after the last application of glue.

Reactivation
Reactivation can be accomplished with MEK, a hot air heat gun, or with heat transfer. MEK reactivation is not the technique that we recommend, because MEK becomes trapped in the glue joint, and keeps the glue from age bonding as rapidly. If the patch is moved at this time by rubbing it out, the bonds can be destroyed. If this technique is to be used, do not over rub-out the patch, and let the patch sit undisturbed as long as possible so that the MEK can find its way out of the glue joint.

Reactivation with Heat Transfer
The best way to reactivate this glue is with heat. MEK reactivation traps MEK in the glue joint, and may destroy some of the chemical bonding. Heat reactivation with hot air guns drive off excess MEK, and if using heat transfer it will not add to the problem. We have been able to transfer heat through three layers of material, making heat transfer reactivation the desirable method for inside patching in the field.

What is Heat Transfer?
Simply, heat transfer is the idea of using a conductive heat source to transfer heat to the patch rather than the convective heat source of a hot air heat gun. We recommend using a large pan full of boiling water that is placed on top of the area to be reactivated. This works well because the pan full of hot water has thermal mass. Simply put it will not cool off too soon, so that the heat can soak through to the glue interface, even through multiple layers. To reactivate the glue it takes only 160 degrees, and boiling water is not hot enough to melt the PVC coating. Because boiling water is around 200 degrees, this technique works very well. Other types of hot objects can be used also. We have used a hot oar pin and it has worked just fine.

When learning patch work with this technique it is advisable to have a large test patch to help determine how much heat to use. Test patches allow you to do a dry run on a piece of fabric to see how this system works.

Glue Procedure
This procedure is for an inside and outside patch. It is great for catastrophic repairs. Generally, I tell people that if you can not get a glue brush inside the hole to do an inside repair, it isn't worth doing an inside patch. I feel that an inside patch has the ability to hold the stress, because the air pressure is behind it, and the outside patch holds the air. Therefore if you screw up, and miss the inside patch a little, don't worry, it is still doing its job of holding the stress that the air pressure is putting on the fabric. Also when doing an inside patch, remember that water is the enemy of glue, and get it all out if possible. Gluing on the inside is difficult. Have someone help hold the material open and apart while the glue is curing. Allow plenty of time for it to cure. It is not easy to get it even on the inside. IF YOUR GLUE IS TOO THICK TO USE, THROW IT AWAY. IT IS TOO OLD. Do not thin the glue with MEK. Heavy coats of this glue work as good as thin coats of glue, and often better, because the glue has not been worked too hard to make it spread out too thin. Remember that this is 80 percent evaporative product, and that it dries out very well.

  1. Wash area with damp MEK rag. Use it sparingly. Some material manufacturers claim that too much MEK will loosen the coating off of the fabric. Washing has the same effect as buffing a hypalon boat or Neoprene boat. If you are gluing to Urethane, scuff the surface by using only a couple of drops of MEK on a Scotch Brite abrasive pad. Use the same kind that are used to clean pots and pans. They are available at automotive stores, and are used in auto body shops. As the MEK dries on the surface it softens the coating slightly, and allows the abrasive pad to scuff it. When gluing encapsulated boats, use a heavier abrasive, no MEK, and wear a dust mask. It takes a little more energy to scuff them properly, and the bond is better if the buff is better. Do not wash the area after buffing. The dust mask will keep the Urethane particles out of your lungs. There is evidence that this dust can be very harmful to your health. Power tools are helpful, but be careful, after the Urethane is gone, the PVC wears through in a hurry. It is possible to burn right through the fabric and make another hole.

  2. Allow time for water vapor that accumulates on surface to evaporate. MEK evaporation promotes water accumulation by cooling down the surface, which causes water vapor to form on the surface.

  3. Mix glue in correct proportion. Use proportional amounts of accelerator and glue that you were given. 2 percent of accelerator to 98 percent glue.

  4. Apply two layers of glue allowing enough time for glue to thoroughly dry out between coats (aprox 15 to 20 min). Note: A milky color in the glue is caused by too much water vapor in the air and will result in a poor bond or no bond at all. The relative humidity must be decreased by use of a makeshift tent and a heat source. Do not attempt to apply a patch when this condition exists, like a rainy night, or at night down close to the river.

  5. Use test pieces to determine when glue becomes inactive. (will not stick) In very warm weather or in the sun, it may not become inactive. It is best to do complicated repairs in the evenings, or in the morning, depending on the anticipated humidity and temperature that will exist at the time.

  6. Align pieces inside and out. Precautions should have been made so that tube will not be glued together. A piece of Wax paper can catch the drips that come off of the glued area inside of the boat.

  7. Reactivate test patch to determine amount of heat required, then reactivate tube patches. Make sure that the patch area is on a flat surface. Align the inside patch by drawing a line down the center of the patch that goes on the inside. This will aid you in proper placement. Remember that it is inactive, so that it can be moved around. Place the top patch on top and align it. Take the hot boiling water off of the stove, and place it on the patch. let it sit for about 2 minutes. Then move it to the next spot on the patch, making sure that the heat zones overlap slightly. While the second heat zone is heating, rub or roll out the first area. DO NOT CHASE BUBBLES OUT TO THE SIDE. POP THEM WITH A PIN. Chasing bubbles destroys the glue bond in the bubble's trail. If the glue is green, this is a sure way to hurt your patch.

  8. Let your patch job sit as long as possible to cure without being disturbed. In one week the glue will be at full cure. In one night it will be at 80 percent cure. If it is done right, and the test patch will tell you this, it should be strong enough in 1 hour or less. Be careful for the first couple of days, and keep the patch covered by a wet towel so that the sun does not reactivate the glue unnecessarily. This is especially important for contact types of adhesives.

NEVER USE A SILICONE PROTECTANT ON AN INFLATABLE BOAT. Using Armor All or some other type of silicone protectant will make your boat impossible to repair, and in some cases have led to rapid deterioration of the adhesive holding it together. This happens on all fabrics. Use of 303 protectant has been proven safe and effective. It has no silicone.


Interfacing Adhesive For a Hypalon to PVC repair
We have been testing the concept of interfacing glues so that hypalon can be glued to PVC. We have determined that our adhesive UR 1087 will work quite well. However there is a little strength gained with the use of contact cement on the hypalon. In fact the UR 1087 sticks so well to the contact cement that it will peal it right off of the hypalon in some cases. We feel that you can't get a better bond than that. The secret to a good bond is how well the Hypalon is buffed. This is a lot of work, but should be done carefully, and completely. No extra care need be given than in a normal Hypalon repair.

To apply a simple PVC drop stitch chamber to a Hypalon floor simply buff the Hypalon real good as you would on a patch. Use two good coats and wait one full day for the contact cement to cure. Then follow the directions for using UR 1087 with the exception that the glued hypalon does not have to be prepped. The UR 1087 will chemically bond to the contact cement because they both use toluene as an evaporative product.

What is great about using UR 1087 is that it will go inactive allowing the repair person to move the parts around so that they can line up properly. (Be sure to use a test piece to ascertain where this point is) Then heat can be applied directly to the glued sides, or to the outside. In the field we prefer a pan of boiling water to reactivate the glue. In this way the floor can be placed inside of the floor of the hypalon boat, and glued in place after it has been properly located.

After the UR1087 has set for a couple of hours and is inactive, place the inflatable floor inside of the old floor (previously glued) and then align the pieces. turn the whole thing upside down on saw horses so that the entire weight of the boat is resting on the inflatable floor. Check alignment one more time. Smooth the bubbles out to the edge. Remember that it is still inactive, and it will not stick. heat the hypalon from the back side of the floor, and allow the heat to soak through the layers of fabric. Smooth out the fabric by hand and then use a roller or a dulled putty knife to apply pressure to obtain a good bond. Try to allow the adhesives to age for a week before using. However this is not absolutely necessary.



Straight Hypalon or neoprene repair

For hypalon repair:
If you are new at repair, and you do not have access to all kinds of adhesives, you will need to find hypalon material to patch with. You can use neoprene material too, and in an advanced course I would tell you why I feel that it is a better substance. For now that would complicate the issue.

Preparation of the material is very very important. Buff the fabric with 36 or 60 grit sand paper. One of my favorite adhesives is a piece of an automotive sanding disk. Go down to the local Automotive Store where they carry painting supplies and ask for a 36 grit open coat sanding disk. It does not matter how big it is because you are going to break it into pieces anyway. These pieces are stiff, and they are easy to use to buff the material. If you avoid the use of power tools, then there is little chance that you will go through the coating and into the fabric. Buff the fabric until all the shiny spots are replaced with deep scratches. Then buff the fabric in the other direction so that the scratches go the other way. With Hypalon there needs to be as much surface area as possible for the glue to hook to. Do this to the patch too. If there are any spots that are not well buffed, it will not stick.

After buffing, brush the rubber dust away with a dry bristle brush. DO NOT wash the patch area with solvent like some recommend. Washing will only decrease the effectiveness of the bond.

Patience is a virtue. After proper prepping, apply contact cement. Use the kind that you get form the hardware store. Weldwood works well. It is important that the cement that you use be the flammable kind. That means that it has toluene in it. Apply an even coat, brushing in the same direction. Do not over brush it. If it puddles up a little that is OK. Now Go to bed and don't mess with it until the next evening. 24 hours!

The next day put a thinner yet not too thin layer of cement on. The cement will go on easier, because it sticks very easily to the cement that you have already applied. If there is a milky color on the surface of the glue use a hair dryer to heat it up slightly so that the milky color disappears. This milky color is moisture that is forming on the patch. By gently heating the moisture is driven away, and you can apply the next coat. Do not allow the glue to get hot enough to bubble. Remember this is day two. It should be well cured glue by now.

Wait after the second layer is applied for at least two hours, and use the hair dryer technique again if necessary. Do not worry about the glue becoming too dry. Applying the parts when the glue is too fresh is the number one mistake that is made when first learning to repair. if there are thick runs or puddles of glue, let it dry over night again.

Apply the patch. This is contact cement, and it means it. If you misalign the patch, and you have let the glue cure out properly, your patch will stick where it is put. If you must remove it you can use an eye dropper full of enamel reducer (xylene) or Toluene to reactivate the glue and pull the patch up. at that point you must re glue and wait again. DO NOT rebuff.

Glue that is too dry can be reactivated by using a rag dampened with toluene or xylene. Therefore it is possible to reactivate your glue after a week or even a month.

Try to finish the repair one week before you need the boat. It takes this type of contact cement one week to reach 70% strength, and one year to reach 95% strength.

Advanced lessons:
Two part contact adhesives cure out much faster. In two days they are well past the 70% cure time. These adhesives are available at Whitewater specialty stores and can be mail ordered. Try using uncured neoprene fabric. The uncured fabric can be buffed easily by softening the coating with a damp toluene rag, and buffing with a wire brush. This makes buffing easy. This material is available from Demaree Inflatables 1800 dib tube. They also carry the best two part cements.


Repairing Small Punctures With a Syringe

Sometimes tubes get punctured by a small wire or a noxious weed. In the southwest we have a nasty little thing called a goat head. It will puncture bicycle tires. It is easy to fix these kinds of holes without compromising the resale value of the boat.

Purchase a Syringe that has a #18 needle. (available at veterinarian and feed stores) Place the needle through the puncture hole. Position the boat so that the needle is at the lowest point. Most of the time the boat must be inflated so that the inside of the boat is not glued together, or that the needle punctures the other side of the boat. It is important that the glue be allowed to puddle up around the hole so that air pressure can force the glue out of the hole and help seal it up. It is also important to be able to remove the plunger and leave the needle in place in the boat. In this way the plunger can be filled several times to insure enough glue in the affected area. Use a paper cup to mix a small amount of glue, and then pinch the top of the paper cup to make a spout. The glue can be poured from easily and slowly into the top of the syringe while holding a finger on the needle end. Replace the plunger, and allow air bubbles to rise to the top before placing the syringe and the needle back together. This is a fairly messy operation. Gloves are recommended. Be careful to hold the needle and syringe together as the plunger is operated. It is easy for them to separate and spray glue on the boat. If this happens have a rag to clean it up quickly before it can do any damage. When pulling the needle out twist it so that the needle itself helps drag some glue into the fabric to help seal the hole.


Recoating Your Boat with Goop

There is a marvelous solvent that is called THF. It is the major component in PVC pipe cement. This solvent will melt PVC and Urethane. You can use this melted compound to actually coat bare spots on a boat, or to help seal up pin holes in the material.

For Urethane, you must melt the coating off of fabric that you use for repair. This works well, because the color can be matched exactly.

For PVC we often recommend that a customer buy some vinyl tubing and cut it into little pieces and apply the solvent. The resulting mixture looks like transparent spaghetti O's.

Desolving of the materials must be done 1 day prior to use, and you must use plastic gloves (food handlers gloves made of polyethylene) to remove the fabric form the solution. Simply grab the fabric and pull it between your fingers (with plastic Gloves on) to squeegee the softened plastic off of the fabric.

Remember that this solvent will evaporate fast. Keep it in a covered container, and always be careful with solvents. Do not use them around open flames like water heater pilot lights. This is strictly an outside activity.

Thin solutions of this material (Tomato soup consistency) with multiple coats. will give the best results. Have enough solvent in the solution so that the mixture is allowed to melt into the existing coating.

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