Crack-and-Crevice Tips, Nozzles and What Each Is For
Why this matters
The label tells you what kind of application is permitted in a given site: a perimeter band, a spot, crack and crevice, a void. The tip on the end of the wand decides what kind of application you actually make. Put a wide fan on a sprayer in a kitchen cabinet and you have made a surface application to food-contact areas, whatever you meant to do and whatever you wrote down. Most indoor label violations a route tech commits are not wrong products; they are right products through the wrong tip. This card is the field key between the hardware and the label wording.
The label words the tip has to match
Read the "Directions for Use" and any definitions block for these terms; many labels define them, and the label's own definition governs.
- Crack and crevice. Small amounts placed into cracks, crevices and openings where insects hide or enter, not onto exposed surfaces. In food-handling areas, many labels allow only this type.
- Spot. A limited area where insects are likely to occur. Some labels cap a spot by a maximum area; if yours does, that cap is the definition.
- Void. Into enclosed spaces: wall voids, hollow legs, behind equipment panels, through an access hole.
- Perimeter or band. A continuous strip along the foundation and the soil or mulch next to it, at the dimensions the label states.
- Broadcast or general surface. Even coverage over an area. Many indoor-use labels prohibit it in occupied or food areas, or allow it only in limited sites.
See related: Perimeter vs Crack-and-Crevice vs Broadcast Application Decision Matrix for choosing among them, and Pesticide Label Reading and Compliance for locating the definitions.
The kit, tip by tip
| Tip | What it delivers | Fits the label type | Common misuse |
|---|---|---|---|
| Pin stream | A narrow solid stream that carries distance and penetrates | Spot into a deep crack, a nest opening at a distance, the back of a gap you cannot reach | Used for a band, it lays a stripe, not coverage; at short range it splashes back |
| Adjustable cone | Pin stream through hollow cone, by turning the tip | Spot treatments; exterior spots on foundation cracks and entry points | Opened wide indoors, it becomes a surface spray with drift |
| Flat fan | A flat, even sheet that lays a uniform band when moved at steady height and pace | Perimeter bands on soil, mulch and the foundation; outdoor surfaces the label allows | Fanning the inside of a cabinet or a baseboard run in a kitchen |
| Crack-and-crevice straw or injector | A small, low-volume jet through a thin tube that enters the gap | Crack and crevice; small voids at a hinge, an escutcheon, a joint | Sweeping it across a surface like a pen; holding it off the crack so liquid lands on the face |
| Bulb duster tip and straw | A puff of dust into a void through a small opening | Void and crack-and-crevice dusting | Squeezing visible piles that repel insects and spread when disturbed |
| Hand or power duster with extension | Dust over a longer reach or larger void | Attic voids, wall voids through an opening, behind equipment, where the label allows | Fogging a living space with dust; dusting an open attic floor beyond the label's site |
| Extension wand | Reach for eaves, high gaps, under decks | Whatever the tip on its end delivers, from farther away | Spraying overhead so drift and drips come back on the applicator |
What each tip is actually for
Pin stream. Its job is reach. A pin stream into the deep end of a gap behind an exterior light fixture puts product where a cone would only wet the face. Outdoors on a perimeter, a pin stream laid along a foundation gives you a narrow line, which is not the band the label describes; switch to a fan for the band.
Adjustable cone. The workhorse for exterior spots: foundation cracks, around penetrations, at an entry point the band does not cover well. The danger is that the same tip, opened up, is a coarse surface sprayer. Keep it at the narrow end indoors, and if the label allows only crack-and-crevice in the room you are in, it should not be on the wand at all.
Flat fan. Built for uniform bands. Held at a steady height and moved at a steady pace, it puts the same volume on every square foot, which is the whole point of the output math in Sprayer Output and Tank Mix Math Worked From the Label. A fan tip's angle and orifice size decide its output; a measured output is only true for the tip you tested.
Crack-and-crevice straw. The tip that makes indoor work label-compliant. The straw goes into the gap, the trigger is a short burst, and the liquid stays inside. Done right, the treated surfaces look untouched. Done wrong, there is a wet line on the cabinet face next to the hinge, which is a surface application.
Dusters. Dust belongs in voids, where it stays dry and lasts. A thin, nearly invisible film inside the void is effective; a visible pile is not more effective, it is a repellent barrier insects walk around and a residue that drifts when someone opens the panel. Maintenance of the bulb duster itself is in How to Clean, Fill and Maintain a Bulb Duster.
Void dusting behind electrical covers
Dusting a wall void through an outlet or switch box is common in roach and ant work, and it is the one place on this card where the hazard is not the pesticide. Before you remove a cover plate, turn off the circuit at the panel, lock or tag it where you can, and prove the box dead with a two-pole tester or meter (a non-contact tester alone does not prove it) that you checked on a known live outlet first, then check it again on that live outlet afterward. Use a nonconductive duster tip and never push a metal tip or wand into a box. Dust the void around the box, not the terminals. Afterward, reinstall the cover, restore the circuit, and confirm the outlet or switch works with a tester or a lamp before you leave. Where the label does not list wall voids, or where wiring is damaged, do not dust there at all; note it and refer the wiring to an electrician. Work practices for this are in 29 CFR 1910.333, and the test-before-touch sequence in NFPA 70E (current edition).
Worked example: one stop, five tip changes
The stop: a single-family home on quarterly service. Inside, a light German cockroach problem under the kitchen sink and behind the dishwasher; outside, odorous house ants trailing along the back foundation. The tech carries a backpack sprayer with interchangeable tips, a compressed-air sprayer with a crack-and-crevice straw, and a bulb duster, and wears the PPE each product's label requires for applicators.
- Exterior band, back foundation. Flat fan on the backpack, held at a steady height, moved at the pace the tech's catch test and the label's application volume set. Why a fan: the label calls for a band, and only a fan lays one evenly.
- Exterior spots. He switches the backpack to the adjustable cone at the narrow end and spot-treats a foundation crack where the ant trail disappears and the gap around the hose bib, both sites the label lists for spot treatment. Why not the fan: those are points, not bands.
- Weep holes. The product's label lists exterior cracks and openings but not wall voids, so he does not inject into the weeps. He notes them on the record. Why: the tip could reach, but the label decides whether he may.
- Kitchen, under the sink. The indoor product's label allows only crack-and-crevice in food-handling areas. He uses the compressed-air sprayer with the crack-and-crevice straw: into the gap where the drain pipe enters the wall (around the escutcheon), into the cabinet's back joints, into the hinge gaps. No surface is wet when he finishes. Gel bait placement in the same kitchen follows How to Place Gel Bait in a Kitchen, and the spray placements stay clear of the bait so the two do not contaminate each other.
- Void behind the dishwasher. The dust label lists wall voids and spaces behind equipment. He uses the bulb duster with its straw through the gap at the side of the dishwasher toe-kick, a short puff into the void behind, keeping the nonconductive straw away from the dishwasher's electrical connection box at the front of the toe-kick space. No electrical cover is removed on this stop, so the de-energize sequence is not triggered.
What the previous tech did. The account's last record shows the indoor product applied as "baseboards and cabinets", and the customer had complained about a film inside the cabinets. The likely cause is a fan or open cone used inside the cabinets, a surface application in a food area. That is a label problem and a customer problem at once, and the fix is the tip, not a different product.
What would change the tip choices. In a commercial kitchen under an audit program, the food-area restriction is the same but the account's own rules may go further, limiting which products may be used at all; see Commercial Food-Handling Facility Audit Requirements (AIB, SQF, BRC). In a garage or crawlspace not used for food, a product whose label allows spot or surface application there may permit the cone, and the straw is no longer required.
Signs the tip was wrong
A wet face beside a crack after a crack-and-crevice treatment. Dust visible on surfaces after a void treatment, or leaking from a switch plate. A band that is dark in stripes rather than evenly wet. A tank that runs out partway around the house because a wide cone was delivering more than the fan the catch test measured. Each of these is the tip telling you it did something other than what the label and the record say. See related: How to Service a Backpack Sprayer Pump, Seals and Nozzle for worn tips that change their pattern.
References
- See related: Perimeter vs Crack-and-Crevice vs Broadcast Application Decision Matrix
- See related: Pesticide Label Reading and Compliance
- See related: Sprayer Output and Tank Mix Math Worked From the Label
- OSHA 29 CFR 1910.333, Selection and Use of Work Practices (electrical)
- NFPA 70E, Standard for Electrical Safety in the Workplace, current edition (verify absence of voltage)