StripSEAL: Tips for Guys Used to Epoxies

Posted by John Bors on Tue, Feb 6, 2018 @ 06:02 AM

StripSEAL is different than epoxy surface seals since it's a polyurea. The trouble is, some field techs use it the same way as an epoxy, which may lead to frustration.If your guys are open-minded and do a couple of things differently, they'll be very happy with its performance—otherwise it wouldn't be one of our top sellers. Biggest reasons to use StripSEAL are:

  • peels easily,
  • fast-curing even in cold weather,
  • won't crack when left overnight,
  • doesn't stink and
  • speed.

Ratio: Cartridges are preferred over bulk (in cans) by 5:1. Why? The convenience factor and the cartridges help achieve the proper proportional ratio. As a polyurea, accuracy to the proper 1:1 ratio is more critical for StripSEAL than for epoxies. Some of our customers buy in the cartridges but throw away the static mixers—they use the cartridge for correct proportioning onto a mixer board where they mix just the right amount.

Manual Gun: An aid in achieving the proper ratio is a good dual component gun. After trying about 10 different models, we found a U.S. patented manual gun that is extremely good at 2 critical actions: 1) excellent ratio control and 2) rapid product acceleration throughout the squeeze action. The patent covers the use of a special spring-action, which aids mixing by applying residual pressure and improves hand leverage.

The best bet for large jobs is an electric or air driven gun because they generally are very heavy duty, get the best ratio and provide instant acceleration of product through the static mixer, which helps eliminate unmixed material spots that don't cure. These guns don't get tired like operator hands so the first cartridge gets mixed the same as the last.

Mixing: StripSEAL in bulk must be ratioed very close to 1:1 or it won't work consistently. Some people use disposable paper cups to get the volume correct. After you get equal volumes, you must mix it for about 30 seconds after you first start to observe the uniform gray color. The extra mixing helps compensate for the fast reaction time.

For cartridges, a good dual-component gun like the model we sell, is essential. Bad guns don't provide sufficient mechanical advantage (you need at least 4 or 5:1 ratio) in the squeeze grip to allow the instantaneous acceleration through the static mixer that helps eliminate insufficiently mixed material.

Partial cartridge: Using a cartridge until empty without stopping will yield the best performance. If you stop more than 2 minutes part way through the cartridge, you should remix the first couple of static mixer quantities on a piece of cardboard with a trowel or simply throw it away. This semi-mixed material in the static mixer is partly reacted and won't set up properly without further manual mixing.

Pressure and time: We suggest that injection pressures be kept below 150 psi for StripSEAL (the lower the better). You can usually inject within about 35-40 minutes, but if you are going to use higher pressures (>100 psi), wait an hour.

Surface prep: StripSEAL has a peel strength up to 400 psi so it should be able to withstand relatively high pressures if you leave sufficient thickness on the surface to offset its flexibility. If your surface is relatively smooth, you should roughen it with a very mild grind or wire brush to give it a toothier profile.

Surface ports: If instead of taped ports, you use glued-on ports, apply the StripSEAL more thickly around the base of the port than with epoxy because it is more flexible and if too thin may allow a bit of weeping. Our surface ports are made with either ABS or nylon (your choice) and work fine with StripSEAL, but in some applications you may need to support them with wire, a toothpick or a cocktail straw.

Blowouts and Stripping: Many field techs apply epoxy seals very thinly. StripSEAL is ineffective if applied this way. It will blow out under higher pressures due to its flexibility. For good containment and easy removal, StripSEAL be applied at a minimum of 1/8" thick and about 1" width.

If you observe mostly well sealed areas with a few pesky soft areas, there are three likely causes:

  • poor ratioing,
  • insufficient mixing when applied or
  • applied too thinly.

Wet substrate: StripSEAL doesn't perform well on damp or wet substrates. The isolated "A" side wants to react with the water before it bonds. One of our other seals with different chemistry should be used under these conditions unless you can get the surface temporarily dry with a hot air gun. Moisture after application doesn't affect the seal.

Tags: news