This edition of Tech Talk addresses one of the most important stages during any detailing or wash regime – the pre wash!
Often overlooked this stage, if done effectively, is one of the best methods for preventing unwanted wash marring and swirls by removing as much dirt and grime as possible without making any contact with the paint.
There are many effective chemicals to use for your pre wash regime such as an all purpose cleaner (APC), citrus degreaser, snow foam and traffic film remover (TFR). These can be applied through two methods, a snow foam lance or a pump spray / trigger spray bottle. Some prefer to use just the one method but here at Devilish Detailing I utilise both methods, I will explain why a little later on.
Snow foams are designed to be used in conjunction with a snow foam lance (although many can also double as a suitable solution to be sprayed). These contain cleaning agents combined with foaming agents that produce a thick blanket of foam to cover the entire vehicle. Whilst the cleaning agents get to work loosening dirt and grime, the foam carries the debris safely away from the paint to then be rinsed away.
A sprayable solution (commonly referred to as pre wash to differentiate between snow foam) also contains cleaning agents that are sprayed onto the vehicle and retain a liquid form. These get to work breaking the bond between dirt and paint. A pre wash solution tends to cling to the paintwork for a longer period than snow foam giving the cleaning agents a prolonged period to break down road grime to then be rinsed away.
When selecting the suitable chemical it is important to keep in mind the strength and most importantly the PH balance. A strong acid or alkaline, although an effective cleaner, will damage any paint protection and in most cases strip wax completely. A chemical that is PH 7 (neutral) is perfectly wax safe. Most manufactures will display this in the information on the bottle. If you would like to test this for yourself simply dilute your product to the recommended dilution ratio, place in a small container and drop a small piece of car wax into the solution. Below, you can see I have tested one of my favourite pre wash products Bilt Hamber Auto Foam at two concentration ratios, one strong and one weak. The wax was left overnight and as you can see has not deteriorated. This tells me that at these dilutions this product is perfectly wax safe.
To demonstrate the effectiveness of a pre wash I have this very dirty BMW 3 Series. It is important to note that this vehicle has no paintwork protection applied.
To start, I apply my pre wash solution liberally over the dry vehicle from the windows down including the wheels and wheel arches. This is left for 5-10 minutes which gives me perfect time to ready my wash buckets and wash mitt for the later washing stage. In hotter temperatures it is important to monitor the product and not allow it to dry, if possible wash your vehicle in the shade and always wash the product off before it gets a chance to dry.
Here I have applied my pre wash to the rear door to demonstrate it’s cleaning strength next to the front passenger door.
When rinsing the product after a suitable dwell time it is important to work methodically, using the pressure from your power washer at the perfect distance that is just enough to start removing the dirt but not too close to risk damaging the paint. This is something you will need to experiment with as the PSI of your power washer may vary.
As you can see we have a panel that is 90% clean. By removing all that dirt and grime without touching the paint we have vastly reduced the amount of dirt that will be picked up by our wash mitt.
The next demonstration shows using a pre wash versus rinsing alone. Half the panel is treated with our pre wash solution and half is left untouched. After 10 minutes dwell time the entire panel was rinsed with equal pressure and attention.
Again as you can see the pre wash solution has got to work breaking down the dirt and road grime so that it can be effortlessly rinsed away where as a high pressure rinse alone wasn’t enough to shift the dirt on the left.
Next up is an application of Bilt Hamber Auto foam through a foam lance diluted at 1:100, left for 5-10 minutes (again not allowing the product to dry in warmer temperatures) and then rinsed methodically from top to bottom. The reason I like to do this is the foam tends to reach more difficult areas, such as grilles and crevices, loosening dirt for the foam to extract. As the foam gets to work this is a great time to agitate badges and other tight areas with a dedicated detailing brush to further remove hidden dirt.
Once the foam is rinsed away and the pre wash stage is complete you can see the considerable difference with the paint 90% clean vastly reducing the amount of dirt to be removed by the wash mitt meaning much less risk of inflicting wash marring or swirls when following up the pre wash with a two bucket wash.
To summarise – both the method of spraying a pre wash solution and snow foam through a lance have their own purpose during the pre wash process. The pre wash solution proving a excellent method for breaking down road grime and dirt to aid in the initial rinse where as a blanket of snow foam gives an opportunity to agitate crevices. If you do not have use of a power washer then the pre wash solution can be sufficient to use alone to remove as much dirt as possible before hand washing. Use a strong setting on hose gun such as the angled fan or jet stream and work methodically to blast away dirt.
Thanks for reading! If you have any questions regarding this article please feel free to contact me at firstname.lastname@example.org or leave a comment below!