Adjusting to the Heat!

While it’s generally understood that temperatures in the colder months can affect the refinish process, it’s also important to remember that adjustments are needed to avoid issues when spraying in higher summer temperatures. Refinish products are generally designed to be used at between 20ºC and 25ºC which is where ‘medium’ hardeners and thinners provide ideal application characteristics. However, those application conditions can change dramatically in the summer months when temperatures often soar. Most workshops aren’t air-conditioned and spray booths don’t include cooling systems to keep the interior at the typical 24ºC application temperature so it’s vital for painters to switch to an appropriate hardener / thinner combination that will ensure user-friendly application characteristics.


Using a thinner / hardener that’s too fast for the ambient temperature makes the job plain hard work for the painter because the paint film simply dries too quickly. That creates a whole host of problems – the paint film doesn’t flow correctly or get a chance to level out, metallics don’t settle correctly leading to mottle and haloing and there’s a loss of gloss and dry edges.


In an ideal world workshop temperatures would be the same all year round – then we wouldn’t need to think about alternative hardeners and thinners. However, because bodyshop conditions vary we need to think carefully before preparing refinish mixtures.

  • Product Data Sheet (PDS) – There is no substitute for checking the PDS. Along with all the other useful information it provides, the PDS will also specify which hardener and thinner to use for the ambient temperature you are applying the product in.
  • Know the ambient temperature – Temperature gauges in the prep area and spray booth will help you make an accurate assessment of the current conditions so you if an adjustment needs to be made.
  • Use all the tools – A set of different hardeners and thinners are developed as integral components of Protec’s high quality paint systems. To help avoid confusion, Protec’s hardener and thinner range uses names that indicate exactly what they are. ‘Low Temp’ is recommended for up to 20°C, ‘Medium’ from 20°C to 30°C and ‘High Temp’ is the best choice for temperatures above 30°C. Note: Protec does not recommend using ‘Low Temp’ hardeners in any of the Protec clearcoat range.

Used correctly, these tools give technicians the ability to continually tailor the products to achieve the same performance no matter what the application conditions – excellent flow and lay down of metallics, along with easy blending and glossy clearcoat finishes.


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