snow foam stains ?

[First Ever Audi]

I've been using a very popular ph neutral snow foam for a while now with great results. The last couple of times I used it, I just rinsed off without following with a proper wash and I've noticed that there are stains on the glass, similar to watermarks. I've had to us polish to clean up the paint and glass polish to sort the glass.....

I this because I didn't wash afterwards and, has anyone else noticed this ?

 

[Pulp84]

I have seen this before on mine when using snow foam but only when it's a hot sunny day and there is part of the car in direct sunlight.

The snow foam drys super quick in this scenario and it leaves these marks your talking about. Usually I just get more water on the car and then wash it as normal and it disappears straight away.

 

[Tank.]

id say almost immediately at a guess the car has been snow foamed when hot or in direct sunlight

also can sometimes be caused by mixing too strong,