The difference between using warm or cold water

Some prefer to wash with warm water, others prefer to wash with cold water. Although the experience of working with it may be different, it is not completely clear what the difference is in the effect it has on a product or a surface.

Why wash with warm or cold water

• It can be more comfortable on your hands
• It can help to dissolve the soap (hot water can “absorb” more and more easily)
• It can help to remove more dirt because of the above
• The surface might need to warmed up

Cold water can also be used for different reasons.

• Cold water is much more easy to get
• Cold water doesn’t need equipment to warm it up
• Not heating it up with equipment means its cheaper
• Some products might be designed to work with cold water
• The surface might need to be cooled down
• Warm water isn’t practical

The difference

It is not completely clear what the effect can be of hot water. To know this for sure you would need to know more about the product used, which can give different results when using certain products. You also need to know better what type of contamination is on the surface and how it bonds with the surface.
However, there are certain theories we can list that can happen.

• The temperature might soften the surface of a wax, making it more sensitive
• The temperature might have an effect on the remaining oils in the wax and have a direct effect on the Hydrophilic properties of wax
• Warm water could improve the performance of soap-like products because of the lowered viscocity and higher solubility
• Warm water could soften up grime and dirt, making it easier to remove
• Cold water will result in less risk of waterspots (mineral deposits)
• Warm water can heat up the surface, which might be desirable in cold weather
• Cold water can cool down a surface, which might be desirable in warm weather
• Certain products might behave slightly different then expected because the temperature of the surface is higher or lower then you expected
• Warm water might be more effective in rinsing off certain chemicals like a tar remover
• If you are using a hose, warm water will make it softer en less stiff
• Warm water has a much lower surface tension, which will help it to clean better (even without soap)

In short we can conclude that cold water is favorable for the durability of a protective product and its sheeting. Hot water will favor the cleaning power of the shampoo.

In conclusion

To put it very simple, the difference between hot or cold water gives us a list of when to use what.
When to use hot water

• When you want to avoid the cold water
• When you want more cleaning power

When to use cold water

• When you want to maximize the durability of the protective product
• When you want more sheeting

This video was taken after washing and rinsing a car with cold water on one side, and warm water on the other side. From the perspective of the viewer, the warm side is on the right.