What is the difference between a pH-neutral shampoo and an alkaline decon shampoo?

A pH-neutral shampoo (pH 6 to 8) is the safe default for routine maintenance washes. It will not strip wax, sealant, or ceramic coating. An alkaline decon shampoo (pH 9 to 12) cleans more aggressively and strips wax and sealants, so it is used before applying a new wax, sealant, or coating so the LSP can bond to bare paint. Do not use an alkaline decon shampoo on a coated car more than once every four months.

Can I use shampoo through a foam cannon for the contact wash stage?

No. Foaming shampoo onto the vehicle through a foam cannon for the contact wash does not work well because the foam falls off the panel before you begin washing. Always load the contact-wash shampoo into the wash bucket, not through the foam cannon. The foam cannon is the right tool for the pre-wash stage, where products are specifically formulated with foam stabilisers to cling to the paint during dwell.

Is it safe to use washing up liquid on my car?

Washing up liquid will clean surface dirt but it strips wax and sealants quickly due to its high cleaning power. It also contains sodium chloride, meaning you are adding salt to the surface while trying to remove road salt, which is counterproductive in winter. Car shampoo exists because it encapsulates dirt safely and provides lubrication so the wash mitt glides without micro-marring. Washing up liquid provides cleaning power but no encapsulation and minimal lubrication.

How do I use the two-bucket wash method correctly?

Keep one bucket with clean shampoo solution and one with plain rinse water, both fitted with grit guards. After washing a panel, rinse and agitate the mitt against the grit guard in the rinse bucket first before returning it to the soap bucket. Never take the mitt from the rinse bucket straight back into clean soapy water, as it still carries significant dirt at that point. Wash top to bottom and re-rinse the mitt often, even partway through a panel.

Do I need to pre-wash before using a shampoo?

Yes, a proper pre-wash is the most important step before any contact wash. Cover the car in pre-wash and jet wash it off so that by the time you make contact the paint already feels clean. This stops you dragging grit across the panels and building up wash marring. After a thorough pre-wash that leaves the paint 80 to 90% clean before contact, a single bucket with a grit guard is sufficient for the contact wash.