This time of year a good pre-wash routine is crucial to get as much dirt off and road salt off as possible before contact or if you are going for a contactless wash.
Generally I would just use snowfoam but that alone isn’t cutting it in these conditions so I’ve been reaching more and more for the citrus pre-wash. In particular Pyramid Citrus is a favourite of mine because of its thick consistency, foaming action and cleaning power.
So the process I’ve always believed to be correct is to pre-rinse as much loose dirt off as possible then apply the citrus so it’s not wasted just loosening dirt that would have been removed without it anyway. Leave that to dwell as long you can without it drying on and then throughly rinse off. If it’s warm outside then layer over some foam to help it work away a few minutes longer.
The other theory I’ve heard some people say works better for them is to spray directly onto the dry dirt so there is no film of water already on the car stopping the chemical reaching the dirt or diluting it further.
To put these to the test then I pre- rinsed half the car and sprayed my citrus solution all round except one small area as a control, after 5 minutes dwelling I rinsed off a small section on each door where the dirt was thickest to swipe and see what dirt remains.
The section just rinsed with water was clearly the dirtiest, the citrus applied to the dry section was a good improvement but slightly dirtier than the pre-rinsed section which in this situation has proven to be the most effective method. before rinsing down the rest of the car I layered over a thick snow foam to see if I could improve this result even further by dwelling for a few more minutes but it did not on this occasion.
So there we have it I will stick to my original preferred method of pre-rinsing before citrus. Although adding snow foam was no benefit on this occasion it would be handy to extend that dwell time if the sun did ever come out again and there was danger of drying out.