aside from a foam gun that attaches to an air compressor, wouldnt one of those vegetable sprayers that you pour chemicals into the jar and then attach to the end of a hose work the same as foam gun ? pour the wash in and then adjust the flow of water to get the right amount of foam ?
In a word yes.
The Foam Gun sprayers sold here are a bit more sophisticated as they're designed and manufactured using brass components. The user also has the option to vary the mixture of soap to water ratio changing the characteristics of the foam bath.
I bought a Wolfgang Foamaster Foam Gun. Because this is for personal or non-commercial use I selected the quart size.
The quality and craftsmanship of the unit is very good. Critical components and mixing valve are made from solid brass. All other components are a high grade plastic ensuring years of trouble free use and satisfaction.
For the most part the unit comes pre-assembeled and its operation is simple and straight forward. Car wash mixing ratios are clearly defined on the plastic cup and the spray nozzle rotates making it easy to reach those hard to get to places.
After mixing the solution according to the directions I hooked it up to the hose and got to work. The foam gun operated flawlessly laying down a sudsy layer of foam that covered the car but was also runny. Keep in mind that this was not a Foam Canon that works with a pressure washer.
The unit operated exactly as designed and its performance was predictable. At no time did it malfunction or under perform.
I always hose down the car prior to washing. This loosens the dust and debris and begins to dissolve water soluble contaminates. Once complete I begin Foaming the surface, the soapy mixture dissolves contamination and particulates which makes washing a breeze.
The sprayers you're referring to are for the most part a one shot deal with no adjustments.