The mix in your snow foam lance bottle is not the concentration that reaches your car. Your pressure washer adds more water as it draws from the bottle. This is the difference in bottle dilution ratio and panel impact ratio, PIR.
In this guide, we explain both using Piste our snow foam and Power Wash, our alkaline shampoo. We also show you how to measure your lance’s output, calculate the amount of concentrate needed and get consistent results without wasting product.
What is the difference between bottle dilution and PIR?
Bottle dilution describes the concentrate and water you put into the foam lance reservoir. For example, 100ml of concentrate topped up with water to a total of 1 litre makes a 10% product mix in the bottle.
Panel impact ratio (PIR) is commonly used to describe the percentage of original concentrate in the liquid delivered from the lance. A 1% PIR means approximately 10ml of concentrate per litre of delivered liquid. It is a practical output concentration, rather than a measurement of how much product stays on the paint.
The lance draws some bottle mixture into the pressure washer’s water flow. That extra dilution is why a 10% bottle mix does not mean 10% on the car. The amount drawn depends on your equipment and settings, so copying someone else’s bottle recipe can give a different result on your driveway.
How much Auto Glanz snow foam should you use?
Piste: our starting point for regular maintenance
For regular pre-washing, Piste pH Neutral Snow Foam loosens dirt and road grime before your wash mitt touches the paint. It is suitable for waxed, sealed and ceramic-coated vehicles when used as directed.
We recommend starting with 50–100ml in a 1-litre foam lance bottle, then filling the remaining space with warm water. That is a 5–10% bottle mix. Adjust within our guidance to suit contamination and your setup. This bottle recommendation is not a 5–10% PIR target.
Power Wash: our deep-cleaning option
When heavier traffic film, grease and winter grime call for a deeper clean, Power Wash alkaline ultra foam shampoo provides stronger cleaning and degreasing action. Our snow-foam instructions specify approximately 1–2% PIR. Use the measurement method below to translate that output target into a bottle recipe for your lance.
We recommend Power Wash when a deep clean is needed. Stronger dilutions can affect existing waxes, sealants or coatings, so choose the strength for the job and check your protection’s care requirements. For routine maintenance, Piste is our straightforward starting point.
How to measure your foam lance’s dilution
You can check the lance’s draw using clean water in its reservoir. Keep the same pressure washer, lance adjustment and operating setup you intend to use for foaming.
- Measure the reservoir water. Add a known volume of clean water to the lance bottle. Record the amount.
- Collect the delivered liquid. Fit the bottle and run the lance into a suitable large container until you have collected a measurable volume. Keep the outlet clear of the container and control splashback. Follow your pressure washer’s operating instructions.
- Measure the reservoir water used. Subtract the amount remaining in the bottle from the starting amount.
- Calculate the bottle-mixture share. Divide the amount drawn from the reservoir by the total amount collected at the outlet. Use the same units for both.
Example: if the lance uses 100ml from its reservoir while delivering 1,000ml in total, its bottle-mixture share is 100 ÷ 1,000 = 0.10, or 10%. The delivered liquid consists of roughly 10% reservoir mixture and 90% additional pressure-washer water.
Repeat the measurement to check consistency. Clean-water testing gives a useful estimate; product viscosity and real operating conditions can affect the draw. Recheck after changing the lance setting, equipment or a blocked/cleaned nozzle. Your own measurement is the starting point for the calculation below.
How to calculate the concentrate needed in your bottle
Once you have measured the share drawn from the bottle, use:
Required bottle concentration (%) = target PIR (%) ÷ bottle-mixture share as a decimal.
Using the example above, the share is 0.10. A 1% output target therefore needs a 1 ÷ 0.10 = 10% bottle mix. For a final 1 litre bottle, measure 100ml of concentrate and add 900ml water.
| Target PIR | Bottle concentration | Concentrate for 1 litre total | Water |
|---|---|---|---|
| 1% | 10% | 100ml | 900ml |
| 1.5% | 15% | 150ml | 850ml |
| 2% | 20% | 200ml | 800ml |
These calculations illustrate Power Wash’s stated 1–2% PIR range on the example setup. For your own bottle mixture, use your measured draw and our instructions for the product you are mixing.
Reverse check: PIR (%) = bottle concentration (%) × bottle-mixture share. A 10% bottle mix multiplied by a 0.10 share gives 1% PIR. If your measured share were 0.05 instead, the same bottle would deliver approximately 0.5% PIR.
Always calculate the final bottle volume. Adding 100ml concentrate to an existing litre of water makes 1,100ml, rather than a 1-litre 10% mix. Measure accurately and leave any headspace required by your bottle.
Does thicker snow foam mean better cleaning?
Our foams are designed to give useful coverage and dwell, but appearance alone cannot tell you the concentration or cleaning result. Measure your mix, then judge the routine by how well it loosens contamination, rinses away and prepares the car for a safe contact wash.
Start with our product guidance and a measured setup before adding more concentrate. For help selecting a formula, read our snow foam selection guide.
Put your measured mix into a safe wash routine
- Work on cool panels out of direct sunlight.
- Follow the product label for mixing, application and protective equipment.
- Apply evenly and allow the instructed dwell time without letting the product dry.
- Rinse thoroughly, then continue with your contact wash as needed.
- Record the product, bottle recipe and lance setting so you can repeat the result.
For coated vehicles, follow our ceramic-coated car wash guide. If water behaviour has deteriorated, our coating-beading guide explains how cleaning can help uncover a coating masked by contamination.
Common questions about snow foam dilution
Does 100ml in a 1-litre bottle mean 10% on the car?
No. It makes a 10% bottle mix when the final volume is 1 litre. The pressure washer adds more water, so the delivered concentration is lower. Measure the lance’s draw to estimate the PIR.
Is a 1% PIR the same as a 100:1 bottle mix?
No. PIR describes delivered concentration. A bottle ratio describes the ingredients in the reservoir and must state which number refers to water. Even before lance dilution, one part product plus 100 parts water is approximately 0.99% product, not exactly 1%.
Should every Auto Glanz foam be used at the same PIR?
No. Follow the directions for your chosen formula. Piste’s instructions give a bottle starting point; Power Wash specifies approximately 1–2% PIR for pre-washing. Keep bucket-wash directions separate from lance directions.
Why does the same bottle recipe produce different results?
Lance adjustment, water flow, equipment condition and product draw can change the delivered mix. Check your settings and repeat the draw measurement before assuming the formula needs more concentrate.
Can I use more concentrate if the car is very dirty?
Work within our product instructions and choose the formula for the contamination. Piste suits regular maintenance, while Power Wash gives us a deep-cleaning option for heavier grime. Choosing the right formula and dilution helps you clean effectively without using more product than the job needs.
Need help setting up your Auto Glanz wash?
Speak to our team with your product, pressure washer and foam lance details. If you have measured the reservoir draw and total output, include those figures too. We can help you build a repeatable wash routine that gets the best from your Auto Glanz products.
