OK, my power sprayer just got in.

The water:soap ratio is 20:1 for the sprayer and is fixed at that ratio.

For the soap I'm using, the recommended dilution is one ounce per gallon or 128:1 for hand washing, but they make no mention as to their strength recommendations for power sprayers.

If my math is right, I need to dilute my soap to 6.4:1 (128/20) prior to adding to my power sprayer in order to have it spray at recommended strength for hand washing at the end of the day.

Are hand/power washing soap strengths the same or are there tweaks I need to make in terms of strengths to get a nice lathery foam or is this the math I should use first and then adjust accordingly from there.

Also, my sprayer is missing an obvious on/off valve for the soap so I can't switch into a rinse mode when I want. How much soap solution should I add to the tank so I can run out at the right time to transition into a rinse mode after lathering?





I'm sure it's not a huge deal to be off a bit on the mix but I was hoping someone may have gone through this already and perhaps can help me save some experimentation.

 

If you're using an onboard detergent container from your pressure washer you will not get a nice lathery foam. You need a foam cannon that attaches to the end of your wand for that.

What sprayer did you buy?

 

Ryobi electric 1600psi 1.2gpm.

 

I've never used my power sprayer with soap - I usually give the car a spray to get off the crap, then do the soapy bit by hand, then spray off with the power sprayer (or a normal hose, because the higher volume of water works better to get rid of the suds). The power sprayer is awesome to get brake dust off and you can get essentially inside the wheel (I mean behind the spokes) but you do have to be careful with them and they arent really recommended for the duco or the wheels for that matter. Also the spraying gets most of the crud off but you still need to sponge clean the car, in my experience.

But then your maths is right - you'd need to dilute the soap about 6 to 1 before you put it in the detergent tank. Apparently some detergents are not recommended for power washers.

As for the question of how long would it last, it really depends on how much water is going through the washer. I put a mixer/sprayer on my hose to put white oil on our fruit trees. Once I turn the tap up, I'll go through the tank in like 2 minutes (probably spraying 30 litres a minute), when the same tank would last a half hour with a hand sprayer which would be lucky to spray 3 litres a minute.

But if your mix rate is 20/1, and your tank is (say) 1 litre, and your sprayer is running at 7l/min which most do, then my maths (should I mention I dropped maths in my last few years of school?) has it that you would be using about 350ml a minute, so the tank will last about 3 minutes.

 

What I meant was - when putting soap into the tank, since I don't have a on/off valve for this tank, how much soap should I put into the tank so I can purposely run out of soap and begin automatically rinsing after the soap is gone. Kind of like replicating a stall type, self serve drive-in car wash.

So let's say I wanted 5 minutes of soapy water before the tank empties.

So to your point, @ 1.2gpm, @ 20:1, the question is how much soap solution goes through the sprayer per minute.

If were running @ 1.2gpm, theres 153oz of soapy water running through the sprayer per minute. Of that volume, 5% of the solution is soap (20:1), that would mean 8oz of this total is from the soap tank per minute. So for 5 minutes of soap, the math says I would need 40oz (8oz x 5 mins) of soap in the tank right?

Seems awfully high...I must be doing something wrong.

Man I'm sending this thing back. I thought it would make my life easier!

 

You need to know both the water flow rate through the pump as well as the soap tank draw rate. Post that and we can do some calculations based on recommended dilution rate.
Do you have the foam wand that Nati asked about?

 

For car washing, forget the "soap" in your power washer. Just use it to "power" rinse before lathering up w/ a microfiber mit and a good car wash, then use it to rinse off the soap.

It's a PIA to use the soap dispensers in a power-washer because then you have to rinse the reservoir, pump, hoses, etc. for some time to get back to clear water. It's a waste of time for no benefit.

If you're power-washing a deck, or something else, there may be a good use for that reservoir, but not on a car.

 

Yep, my calculations are the same as yours. 5 minutes worth would need about 1.2 litres.

But as I mentioned, I think you'd be wasting your time. You'd still have a dirty car unless someone sponges it off, or as Foosh mentioned, uses a mit.

I'd can the detergent bottle and just use the sprayer (from a safe distance) for the initial hose down and especially the wheels. It is just awesome for the wheels, especially the fiddly ones that are a PITA to do by hand.

I've used a power washer on my cars for about 5 years with no problems, but you cant use the nozzle that has the spinning ball bearing, and you cant have it too close to the paintwork. I figure if it hurts my foot to spray it, it is too hard for the car, so work on that to fgure out a safe distance and dont lose a toe in the process.

If I had to use soap in a power washer, I'd probably spray it first to get rid of the crud and brake dust, then attach the bottle, give it its lather, then go over the car with a sponge. On that basis you'd probably only need 2 minutes worth of soap, so about a third of a bottle.

My business partners would crap themselves laughing if they saw me giving advice on maths problems.

 

Echoing again some of the above, your car will not be clean if all you do is suds it and rinse it with a pressure washer.

If you want foam that stands on the car, you'll need a foam cannon such as the common one by MTM Hydro. It's about $60. Specifically for your washer, you want the cannon rated for a max of 2500 psi. If you get the one intended for gas washers, and thus rated for higher PSI, it won't work as well.

1600 psi is not very much to begin with. I'm not sure this will satisfy you in the long run. Mine is 2000 and it will foam pretty well, all things considered, but it doesn't match a gas unit at ~3500 psi.

 

You guys glossed over the plan where I said I'd soap her up, stop the sprayer to mitt her down, then rinse with clear water due to the empty soap tank.

Wouldn't this technique be the perfect solution?

 

And you forgot the part that your pressure washer will be contaminated w/ soap, and it will take a long time to flush it out so that you're back to clear water.

If you're willing to spend all the extra time, it will work, but it's not worth the trouble for zero benefit.

 

So Foosh, you're saying even after the soaps all gone, the water running through it still isn't clean? Just bad design then. There shouldn't be a gray area about soapy and clean water. It should be binary. Wash or rinse

Definitely going back then.

 

All the water coming into your power-washer runs through the soap tank, whether there's soap in it or not. It then goes into the pump, through the hose, and out the wand. Even when the soap tank is emptied, it takes quite a while to flush out the system.

Bad design no . . . just the way they all work. It's a very useful tool because you get a much better initial rinse, and most of the loose crud comes off before you ever soap the car. It's far more effective than a garden hose.

I've never put soap in power-washer to wash a car, finding it completely unnecessary. My car wash solution stays in a bucket w/ a mit.

Go ahead and try it. After you do, I'm fairly confident you won't do it again, unless you just enjoy spending more time washing your car. :-)

 

My sprayer has a different design. The detergent tank has a siphon tube in it. When you turn the knob to soap, it draws through the siphon. Turn the knob the other way to stop the draw on the detergent and get back to rinsing (after purging what's in the pressure line and the wand). Perfect for patio furniture; not precise enough for my car.

My foam cannon:
https://www.amazon.com/Professional-...dro+foam+lance

My washer:
https://www.amazon.com/dp/B00CPGMUXW...re+joe+spx3000

 

+1 don't put soap in the pressure washer tank. Foam cannon only way to go.

Use a decent auto shampoo too like one of these. The ones at auto stores are all crap.

https://www.amazon.com/Adams-NEW-Was...s+auto+shampoo

https://www.amazon.com/Chemical-Guys...ydew+snow+foam

 

I have a cheap power washer I got at Lowe's. There's no switch for soap, but it only draws soap with the lowest pressure nozzle, the others only spray water, allegedly.

 

I like the 2 bucket with mitt approach even though I have a very good power washer.