The Gel System

Repel Gel — you will also see it sold as Mint Repel — is built from two naturally derived component families, and it is worth understanding what each one is doing.

The active side is derived from mentha arvensis, wild mint. This is the species behind the commercial menthol trade, and its oil is sharper than the peppermint most people picture. It is the component rodents respond to: a saturated mint environment interferes with the scent information a small prey animal uses to judge whether a dark cavity is worth entering.

The carrier side is derived from mentha, cornmint oil. This is what makes it a gel rather than a liquid, and it is the half of the formula that determines service life. It gives the product enough body to hold position on a frame rail, and enough internal volume to keep releasing actives after the surface has offloaded its first dose.

Read those two paragraphs in the other order and you have the design brief: pick an active that works, then solve the much harder problem of keeping it on a moving, weathering, salt-blasted underbody for a whole storage season.

A gel raises an obvious question about equipment, so here is the answer: Repel Gel can be sprayed on or brushed on. Neither is the official method. They are two ways of putting the same material on the same steel.

One clarification first, since this site spends a lot of words on why a gel beats a spray. That argument is about what the material is, not about how it leaves the container. A thin liquid is still a thin liquid after it lands. Spraying a gel puts a gel on the metal.

The rest falls straight out of the delivery argument. The property that makes a gel hold position on an overhead surface — body, structure, resistance to running — is the same property that lets you load a brush with it and work it into a seam. A thin liquid sprays beautifully and brushes into nothing. A gel does both.

Brush when you are doing one unit, when you do not own a rig, or when you want deliberate build somewhere specific: the fastener line along a belly pan, the collar around a wiring pass-through, the return inside a wheel well. A brush is slower and more precise, and those zones want precision.

Spray when volume or geometry makes the speed worth it — a long enclosed belly pan, a row of units before a season, a shop that already owns the equipment and the bay.

The practical consequence matters more than it sounds: nobody has to buy capital equipment to use this product. A dealership can treat units with a brush and a creeper before it ever decides whether a spray setup is worth budgeting for. Request the current technical data sheet and we will include the equipment guidance in effect.

A gel that adheres well is the entire value proposition, so prep is not optional here the way it sometimes is with a pouch you just hang up.

Degrease first. An underbody with any road miles on it is coated in an oily film of road grime, and nothing bonds to that. Wash it, degrease it — Super Orange Cleaner is what we use — and rinse. Then let it dry completely.

Remove what is already falling off. Flaking rubberized undercoat, scaling rust, and packed mud in the frame channels have to go. A coating applied over loose material adheres to the loose material, and leaves with it.

Chase down active water. Wet insulation inside a belly pan means a leak. Coating over it seals in a rot problem you will meet again later. Fix the leak first — that is a better use of the day than the coating is.

Map the penetrations before you start. Get on a creeper and note every wiring pass-through, plumbing penetration, slide-out opening, and belly pan seam. Those are the priority zones for build, and it is much easier to plan them from the ground than to discover them mid-application.

We deliberately do not publish a coverage rate on this page. Coverage on an underbody varies enormously with configuration — an open-frame utility trailer and a fully enclosed Class A belly pan of the same length are completely different jobs — and a number posted on a web page has a way of outliving the formulation it described.

What we do instead: send you the current technical data sheet, and help you work quantity for your actual unit or fleet mix. If you are quoting a storage-lot add-on or building a dealer PDI package, you need a defensible per-unit number, and the data sheet plus a look at your typical unit will get you there properly.

The same applies to reapplication. Any scent-based product depletes; the gel carrier is what stretches the interval from weeks into seasons. Most operations tie the refresh to the storage cycle. For the actual interval guidance, ask for the TDS.