Advice on the best or worst foam cannons for washing grotty cars
Do you really need detergent based foams for cleaning?
If they are detergent based, see that you cars manual says. Many manufacturers don’t recommend use of detergents (including those marketed as being suitable for cars) as they strip the protective layer on the paint surface (including any wax or polishes one may use to maintain the paint finish) and will also remove any surface coating on the inside of panels or on welds/joints which can lead to premature rusting/corrosion.
We knew a panel beater in Brisbane who strongly advised against using any detergents as it causes paints to deteriorate quicker and accelerate corrosion.
He also said not to use a high pressure cleaner. Using high pressure cleaners isn’t also recommended by many manufacturers as they can strip the surface paint coatings, cause damage to seals and plastics, cause water penetration into areas where water shouldn’t go and can remove decals.
Every since receiving his advice, we only use water under mains pressure. If the underside of the car is dirty from off road/gravel roads. put a sprinkler on under the car and over a short time (e.g. 30 minutes) most of the lose material will wash off.
I know that there is a lot of advertising for foam cannons, but that is because it’s (one of) the latest gimmick(s) to hit the market. If you do a search on the best way to clean a dirty car, you will note that most talk about washing by hand. Even Supercheap who sell all sorts of merchandise, including cannons, say wash it by hand. Have a look at this Supercheap page on the right way to wash your car.
The manual for my new (had it a tad over a week) Hyundai recommends a number of times not to use pressure washers on the car.