If you only check one number before buying lighting for a detailing bay, make it CRI. It is more important than wattage, more important than lumens, and it is the spec cheap sellers are most likely to leave off the listing entirely.
What CRI means
CRI stands for Colour Rendering Index. It is a score out of 100 that describes how accurately a light source shows colours compared to natural daylight.
Daylight scores 100 by definition. A good LED scores 90 or above. A budget LED often sits around 70 to 80, and older fluorescent tubes can be worse.
The number does not describe brightness. A CRI 70 light can be blindingly bright and still show you a version of reality with the colour information stripped out of it.
What low CRI actually looks like in a bay
This is easier to understand through symptoms than theory. Under low CRI lighting:
- Reds go flat. A candy red or a deep metallic red looks muddy and brown. Judging whether you have restored gloss becomes guesswork.
- Dark blues read as black. Which makes it much harder to see the difference between a corrected and an uncorrected section.
- Subtle defects hide. Marring, light hazing and the tail end of a correction are all low contrast events. Poor colour rendering reduces contrast further.
- Your photos need rescuing. Skin tones go green, paint colour is wrong, and no amount of white balance correction fully fixes it because the colour information was never captured.
The insidious part is that none of this looks obviously broken. The bay seems bright. You just quietly do slightly worse work and take slightly worse photographs.
Why it matters more in detailing than almost any other trade
Two reasons.
First, paint colour is the product. Your customer is paying for how their car looks. If you cannot accurately see what you are producing, you are working blind on the exact thing they are buying.
Second, correction is a judgement call made at the margins. Deciding whether one more pass is needed, whether the hazing has cleared, whether a section matches the one next to it, all of that depends on seeing fine differences in a reflective surface. Anything that reduces your ability to see contrast makes those calls harder.
R9 and why 90 is not the whole story
Worth knowing if you want to go a level deeper. The headline CRI figure, properly called Ra, is an average across eight pastel test colours. None of them is a strong red.
Strong red is measured separately as R9, and it is where cheap LEDs fall apart. A fitting can score a respectable CRI 85 while having an R9 close to zero, which means it renders almost everything acceptably and reds terribly.
For a detailing bay, ask for R9 as well as Ra. A good fitting will have an R9 above 50 and the best will be higher. If a supplier does not know what R9 is, that tells you something.
How to check before you buy
- Look for CRI stated on the product page. If it is absent, assume it is low, because good CRI is expensive and nobody hides it.
- Look for Ra 90 or above for correction work. Ra 80 is acceptable for wash bays and storage areas.
- Ask about R9 if the work is colour critical.
- Check for flicker at the same time, because the cheap drivers that produce poor CRI usually produce flicker too.
- Be wary of very cheap fittings with enormous lumen claims. Efficiency and colour quality pull against each other, so something has to give.
Where high CRI matters most in your unit
Not every fitting in the building needs to be CRI 90. Spend the money where it counts.
Critical: inspection lighting, tunnel lighting, and the main ceiling array over the correction bay.
Important: wall lighting along the flanks, and anywhere you photograph finished work.
Less critical: storage, office, staff areas and outdoor lighting.
The business case in one paragraph
Good colour rendering means fewer missed defects, which means fewer comebacks. It means faster decisions during correction, which means more cars through the bay. It means photographs that need less editing and sell more work. For a bay running full time, the difference between CRI 80 and CRI 90 lighting is a few hundred pounds up front against months of slightly compromised output.
Frequently asked questions
Can I measure CRI myself?
Proper measurement needs a spectrometer, which is expensive. A practical test is to put a known colour, such as a paint swatch or a red cloth, under the light and compare it to how it looks outside on an overcast day.
Is high CRI lighting less efficient?
Slightly. Higher colour rendering usually costs a little efficiency, so a CRI 90 panel will draw marginally more power for the same light output than a CRI 80 one. For detailing work it is a trade worth making.
Does CRI affect ceramic coating inspection?
Yes. Spotting high spots relies on seeing subtle differences in how a surface reflects, and poor colour rendering reduces exactly that kind of contrast.
All of our detailing focused fittings list their full specification. Browse tunnel lighting and hexagon lighting, or ask us for the exact CRI and R9 figures on any product.