The Koch Chemie GSF Gentle Snow Foam is a pH-neutral pre-wash that forms a thick, clinging foam and is safe on ceramic coating, wax and PPF. You can use it two ways: as a pre-wash in a foam cannon to soak off loose dirt, or diluted in a bucket as a contact shampoo. This guide covers the right dosing and how to keep the foam from drying on.
Why pH-neutral matters
Many pre-wash products are alkaline and clean aggressively, but over time they can break down wax and coatings. GSF is pH-neutral and does not strip the protective layer. That means you can pre-wash at every wash without sacrificing your coating, which makes it the logical choice for protected cars that are washed regularly.
Dilution: foam cannon or hand wash
For the foam cannon or lance, put around 20 to 30 ml of GSF in the mixing bottle and top up with 1 litre of water. More product gives thicker foam, not necessarily more cleaning. As a contact shampoo for hand washing, use around 50 ml in 10 litres of water in the wash bucket. The cherry scent makes the wash pleasant.
How to use it
Rinse off the loose dirt first. Rinse the car with water before you apply foam. This removes sand and grit that would otherwise cause scratches during the wash. Work in the shade on cool paint if you can.
Apply an even foam blanket. Cover the whole car from bottom to top with an even layer of foam. The lower panels are the dirtiest, so give the foam the most time there.
Let it dwell for 3 to 5 minutes. Let the foam dwell for 3 to 5 minutes so it can loosen the dirt. Never let it dry on the paint, especially not in the sun, because dried product leaves residue. If the foam runs off quickly, rinse sooner.
Rinse from top to bottom. Rinse the foam away with a strong jet of water, from top to bottom, so the loosened dirt runs off downward. Then continue with the contact wash using a wash mitt.
GSF as a contact shampoo
No foam cannon? Then use GSF straight in the bucket, around 50 ml in 10 litres of water, and wash with a clean mitt. That way the same coating-safe product also works as your gentle car shampoo.
Common mistakes
Letting the foam dry in the sun, which leaves residue behind.
Skipping the pre-wash and going over dry, gritty dirt with the mitt, which causes scratches.
Thinking snow foam replaces the contact wash. It is a pre-wash that loosens most dirt, after which you still wash by hand.
Overdosing for thicker foam. Thicker foam does not clean better and just wastes product.
New to pre-washing? Read the general explainer on using snow foam first. For the foam you need a foam lance.