High CRI lights for conservation

If you want to know what CRI is? and whether the lights you are interested in are suitable, this article may help enlighten . We have also got the conservator's eye-view on them, read more below.

Strawberry Hill House conservation team chose the Scangrip high CRI lights for condition checking their early 19th century tented ceiling. You can see from the images below that the Scangrip Multimatch 3 and Sunmatch 3 offered the perfect quality of light and level of portability for their needs. But, what should you consider when choosing task/work lights? read some of our tips below.

Conservation high CRI lighting

We’ve put together a 5 point check for choosing conservation work lights.

The view from a conservator

Museum Conservation Services Ltd, a fine art restoration and conservation consultancy based in Cambridgeshire, have used the Scangrip range of lights from PEL on a project where good quality lighting was important. Nicholas Burnett ACR from Museum Conservation Services, shared his thoughts, giving a conservator's eye-view of the Scangrip lights in a practical situation.

Nicholas used the Multi-Match 3, Matchpen and i-Match headtorch, putting them through their paces on-site restoring wallpaper. The conservation work involved re-adhering lifting areas of wallpaper, filling losses and toning the fills to blend in, hence the need for a colour-balanced, excellent light source.

Museum Conservation Services have used a number of different lights on various on site projects and they were impressed by the Scangrip light's CRI and portability. Nicholas performed his own tests to verify the manufacturer's stated CRI values."The CRI of 95 is very good and certainly an improvement on most of the lights we have used on site. High quality fluorescent tubes have a CRI of 98, but where these (Scangrip) lights win-out though is their small size. Transporting large lights that incorporate long, delicate fluorescent tubes to work on site is asking for trouble. We are certainly willing to trade a slightly lower CRI for the smaller footprint, lightness, portability and ruggedness of these lights." Consistency of the lighting is also incredibly important, "The illumination is wonderfully even." he said.

As the range has a number of choices, you can make a decision on which model or models suit you based upon the project or work you expect to use the light for, but each has it's own advantages, as Nicholas discovered;

  • On the Multimatch R"The largest light (Multimatch R) has its own adjustable stand but is light enough to be hand-held. The presence of magnets in the stand add to its versatility. This lamp was particularly good for illuminating large areas."
  • On the i-Match head torch "The headlamp has obvious advantages in keeping one’s hands free. An unexpected and convenient feature was the motion sensor that would turn the light on or off with a wave of the hand."
  • On the Matchpen torch; "The Matchpen light has an adjustable focus and comes into its own for examination, especially for raking light. The even distribution of light was particularly useful when taking photographs in low-light situations where using flash and/or a tripod was either impractical/not allowed. "

Even spread of light

As you can see from the above image, when working on or inspecting surfaces it’s important that the lighting is consistent from middle to edge of the beam. Disruptions and inconsistency in the illumination can make condition checking or repairs difficult when trying to match colours and texture, identifying damage, dirt or staining. The lamp used in the picture is the Multimatch 3.

Can you actually use them where you need them?

ip rated work light

Cabled lighting can restrict options when working at height (ladders or towers), outdoors or in a building/space without access to power. Battery powered lighting can be far more flexible, but can be exhausted if working for long periods, so extra battery packs may be required. If working outside, in a dusty area or using water, paint or solvent which might splash it's important to choose a light with a an appropriate level of protection. Our Scangrip range of work lights are all IP67 rated against water and dust. The Matchpen R features a solvent resistant lens.

Accuracy of colour rendering – what is CRI?

CRI (Colour rendering index) is a score based upon a light source’s ability to accurately illuminate colours compared to daylight. CRI scores range from 0-100 with the best quality lights being scored 95 and over. In order to reach a score of 100 a light source would have to completely match the spectrum of daylight. So, what are the issues with CRI? In lower quality, lower rated lights, subtle colour differences can be missed or totally misinterpreted. This is also called ‘illuminant metamerism’ – a poor light source can allow two different colours to appear the same (e.g. navy blue & black may appear the same), or completely change the appearance of particular colours (e.g. green to yellow, red to brown). Staining, mould or other damage may not be visible or less visible.
CRI light chart Scangrip CRI+ is an upgrade on the standard CRI score and includes other colours. The standard CRI value is calculated as an average of the first 8 R-values out of 15. This means that e.g. the R9 (red) value, which is important for correct colour recognition, is not taken into consideration for a standard lamp's CRI value. The Scangrip lights CRI+ is defined as an average of all 15 R-values. When working with textiles (like the tented ceiling shown), paint or other coloured surfaces high CRI lighting is a must-have. Our range of high CRI lights can be seen here


handheld work lamp

Colour temperature

light colour explainer

Colour temperature is measured in K (kelvins) and usually stated with any lighting source. A range of between 2500k (warm/yellow) and 6500k (cool/blue) are standard. Sunlight has an approximate colour temperature of 6000k/6500K and this is the colour required for most conservation work. Scangrip lights are capable of cycling through these colour temperatures. This can reveal discrepancies in some fabrics and repairs and allows objects to be viewed in the colour which will more closely match the display lighting.

matchpen torch raking light

Raking light

In order to reveal surface characteristics of some materials it may be necessary to use raking light across the surface. Raking light can reveal damage or deterioration that may not otherwise be visible. A sufficiently compact light source is required to enable the light to be sent across the surface so a hand torch like the Matchpen R is ideal.

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