Don't Forget About Dwell Time
Here's something that gets overlooked constantly: Chemicals need time to work.
Spraying a cleaner onto a dirty surface and immediately rinsing it away may not give the chemistry enough time to do its job.
Dwell time allows the chemical to interact with the contamination and loosen it before rinsing. That doesn't mean letting the chemical dry on the surface. hose are two very different things.
The correct dwell time depends on the product, concentration, temperature, surface, and contaminant. Follow the chemical manufacturer's directions rather than assuming that longer is always better.
More Chemical Isn't Better
This is one of the easiest mistakes to make. If a little cleaner helped, then more cleaner must help more, right? Not necessarily.
Over-concentrating chemicals can:
- Damage surfaces
- Leave residues
- Increase rinse requirements
- Increase chemical costs
- Increase environmental concerns
- Damage plants and landscaping
- Create unnecessary exposure for workers
- Increase the likelihood of equipment problems
You're not trying to win a chemistry contest. You're trying to clean the surface effectively and leave it in better condition than you found it.
Your Pressure Washer Doesn't Like Every Chemical You Do
Another consideration is your equipment.
Pressure washers are designed to handle specific types of water and cleaning products. Introducing the wrong chemical into the wrong part of the machine can result in premature wear, seal damage, corrosion, or other problems.
This is especially important when you're dealing with:
- Downstream injectors
- Chemical injectors
- Pumps
- Valves
- Hoses
- Guns
- Seals and O-rings
-
Tanks and plumbing
Not every chemical should be run through the pressure washer pump. In many applications, downstream injection is preferred because the chemical is introduced after the pump. That can reduce chemical exposure to components that weren't designed to handle it. But even then, compatibility matters.
After using chemicals, proper rinsing and equipment maintenance aren't optional. Leaving chemical residue in hoses, injectors, guns, or other components can lead to problems later.
If you're unsure whether a particular chemical is compatible with your equipment, check the chemical and equipment specifications—or ask someone who knows the equipment before you find out the expensive way.
Think About Where the Water Goes
Cleaning doesn't end when the surface looks good. You've also got to think about the water and chemicals leaving the jobsite. Depending on the application, runoff can contain:
- Oils and grease
- Detergents
- Heavy metals
- Paint residues
- Dirt and sediment
- Biological contaminants
- Other pollutants
That runoff shouldn't automatically go down the nearest storm drain. Environmental requirements vary by location and application, so contractors need to understand the requirements that apply to their work and have a plan for containing, recovering, treating, or properly disposing of wastewater when necessary.
This is one of those situations where saving a few minutes on cleanup can turn into a much bigger headache. Know where your wastewater is going before you start washing.
When Chemicals Are Actually a Mistake
There are plenty of jobs where chemicals aren't necessary. If you're removing loose dirt from a durable surface, for example, water and appropriate pressure may be all that's required.
Using chemicals when they don't provide a meaningful benefit adds cost and complexity without improving the job.
Chemicals can also be a mistake when:
- The substrate is chemically sensitive
- The cleaner isn't compatible with the coating
- Runoff can't be properly managed
- The operator doesn't understand the required dilution
- The product is being used outside its intended application
- The operator is using chemistry to compensate for the wrong equipment or technique
Sometimes the right answer isn't a stronger cleaner. Sometimes it's better equipment, the correct nozzle, hotter water, more appropriate pressure, better technique, or simply more time.
The Right Cleaning Process Is a System
A professional pressure-washing setup isn't just a pump that makes a lot of PSI. Think about the entire cleaning system:
Water + temperature + pressure + flow + nozzle + chemical + dwell time + agitation + rinse + wastewater management
Changing one part can affect the others. For example, increasing pressure isn't necessarily going to improve cleaning if the real problem is inadequate flow or the wrong chemical.
Likewise, dumping more detergent onto a surface isn't going to fix a process that's using the wrong nozzle or not allowing enough dwell time.
The best results usually come from getting all the pieces working together.
Don't Let a Dirty Surface Become a Bigger Problem
The purpose of pressure washing isn't to prove how much pressure your machine can produce.
It's to clean the surface efficiently without damaging the surface, equipment, or surrounding environment. That means knowing when to use chemistry—and knowing when to leave it on the shelf.
At Youngstown Spray Equipment, we help contractors and maintenance professionals choose the right equipment, accessories, chemicals, and setup for the job at hand. Sometimes that means recommending a chemical. Sometimes it means recommending a different nozzle, setup, or cleaning method.
We're not interested in selling you something you don't need. We're interested in helping you get the job done right.
If you're not sure what chemical, pressure washer, injector, nozzle, or setup makes sense for your next cleaning application, give us a call. We can help you work through the variables before you put the wrong combination to work on the jobsite.