Orifice size directly controls how much water your pressure washer can push through the nozzle - and that restriction is what determines your working PSI. A larger orifice allows more water to pass through with less restriction. That typically increases water flow (L/min) but lowers pressure slightly because the pump isn’t working as hard. A smaller orifice does the opposite - it restricts the outlet more, which increases working pressure but reduces overall water flow.

The key thing to understand is that you’re not “adding” pressure by going smaller - you’re increasing that resistance. That extra restriction makes the pump work harder, which is why selecting the correct size is important. For detailing, we usually aim for a balanced setup suited to your machine with strong, safe pressure with healthy water flow - rather than simply chasing the highest PSI or water flow possible.

One of the biggest things to be mindful of is how much force a pressure washer can generate - especially with narrower spray angles. A tight angle concentrates the impact into a smaller area, which increases the force on the surface. That’s great for heavy cleaning, or even things like cleaning the deck or driveway, but it can be risky on paintwork if you’re too close. For regular detailing, wider angles are generally safer and more forgiving.
It’s also good practice to start your pressure washer with the gun pointed away from the vehicle. If there’s any pressure surge, air in the line, or an incorrect nozzle fitted, you don’t want that first burst hitting paint or trim and make sure the nozzle is properly seated in the quick connect fitting before use.

For detailing, we generally recommend sticking to wider spray angles - something in the 25° to 40° range is ideal for most paintwork. A wider angle spreads the water out over a larger area, making it safer and easier giving you plenty of cleaning power. It allows you to rinse efficiently without concentrating too much force in one spot.

Narrower angles, like 15° or especially 0°, concentrate the water into a much tighter stream. That dramatically increases impact force, which can be useful for heavy-duty cleaning around the home - things like concrete, driveways, brickwork or stubborn grime on hard surfaces. But for regular vehicle washing, those tighter angles can be too aggressive if you’re not careful.

As a general rule: wider for paint, narrower for hard surfaces - and always keep a sensible distance from the surface you’re cleaning.