Did you know that X-rays imaging is the oldest physical analysis technique used in art?
It’s been 130 years since it was first applied, and it’s become so established that the phrase “X-ray scanned” has even entered everyday language — meaning something has been examined in depth!
At Art-Test, X-rays imaging of paintings is among the most requested analyses.
And now there’s big news: at Art-Test two brand-new X-ray machines are ready for use, drastically reducing waiting times for our clients.
But what does an X-ray really reveal? And why is it so important?
Let’s shed some light on the topic — and debunk a few myths.
🎨 X-radiography vs. Reflectography: Let’s clarify
These two techniques are often confused — not least because both produce black-and-white images and are used to investigate the “hidden layers” of a painting.
But they’re based on different physical principles and explore different depths of the artwork.
Infrared reflectography (IRR) relies on the partial transparency of certain pigments to infrared rays and is mainly used to reveal what lies beneath the visible paint layer — particularly the underdrawing.
It’s especially effective when the drawing was made with carbon-based materials (like pencil or charcoal) and, under certain conditions, with red chalk (sanguine).
X-radiography, on the other hand, is based on how much X-rays are absorbed depending on the density and atomic number (Z) of the materials they pass through.
X-rays fully penetrate the artwork and create an image that reflects the total attenuation of the beam across the entire structure.
For example:
- Lead, found in lead white (a pigment widely used in the past) with Z = 82, is highly radiopaque and appears very bright in X-rays.
- Zinc, found in zinc white (a more modern pigment) with Z = 30, is less radiopaque and appears darker.
- Varnishes and organic binders, with very low Z values (around 6–8), are generally radiotransparent.
- Thickness matters too: a thick wood panel will block more X-rays than a thinner one, even if they are made of the same type of wood.
🔍 Why is it so useful?
X-radiography is essential for understanding how a painting was created and for assessing its state of preservation.
Unlike reflectography, which stops at surface layers, radiography can reveal deep hidden elements such as alterations, restorations, or even entirely different paintings beneath the surface.
🎯 A recent case?
After careful visual observation and IR reflectography at 1700 nm, it was the X-ray that finally revealed a completely different subject hidden beneath the current paint layer.
A painting signed Claude Monet
⚙️ 🧪 Tailored Diagnostics (Now More Accessible)
Art-Test is always by your side to help choose the most appropriate investigation for each artwork.
We can also carry out preliminary tests to design a personalized and truly effective diagnostic campaign with you.
📉 And there’s more: throughout 2025, X-radiography services will be available at discounted rates.
Take advantage of it!
