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Powder Coating the Candy Red Frame

by | Jun 7, 2012 | 0 comments

Love at first sight

On a recent visit to our powder coaters, I fell in love with a Candy Tiger Red colour.  This particular paint falls under the “very rare” category and is imported on special order per kilogram only.  The powders we usually work with are manufactured locally and is sold in 20kg boxes, so this really is as fancy as you can go.

Experiments on powder coating

The next step was to find out if the powder could handle the heat generated by our machines.  Even though we install heat insulating ceramic wool around the roast chamber and isolate all panels with further ceramic strips, the exterior still gets quite hot.  The side temperatures settles at around 70 degrees Celsius while the hopper and front door reaches 120 degrees after a few hours of continuous roasting.

The test results were conducted in the manufacturer’s laboratory.  They coated a 3mm mild steel plate and left it in the oven for 48 hours at 170 degrees.  Testing was done at 24 hour intervals using a spectrometer to measure the exact colour deflection (similar to what the Agtron does) of the plate after continuous heating   The plate passed the test easily and the paint kept its integrity although the paint did discolour quite badly.  The test conditions represented an absolute worst case scenario, but we’d rather be safe than sorry!

Thank goodness for trial runs

The next step was to coat a small sample plate to see how the paint reacts in the real world.  Thank goodness we did!  The plate had serious blemishes on it; the translucent paint shows any discolouration from the steel beneath it. After a few more phone calls, we bought out a box of chrome coloured powder and coated the entire roaster in a shiny grey colour before applying the Candy Tiger Red paint.  This would cover the grinder marks on the frame and also make the whole roaster lighter in colour.  Here are a few photos of the frame in the oven.

A roaster gets attitude

In the photos below you can see how the powder is applied.  An electrostatic charged paint gun is used to coat the earthed steel frames.  This gives the particles a negative charge while the frame is neutral.  This principle creates a magnetic bond between the particles and the frame, allowing them to cling onto the frame in a uniform thickness.  Germany, the painter, gently on each panel and reapplies powder as he sees fit.  His experience makes the whole process more reliable and consistent and ensures that hole is left out of the loop.

By: Neil Maree

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  1. The Big Red Roaster | Hand Crafted Coffee Roasting Machines - [...] some discussion on colour and specs, we agreed on building a Candy Tiger Red roaster with a custom roast…

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