25 Scientific Tests on the Shroud of Turin

A Century of Analysis and Controversy

(All photographs courtesy STURP member Barrie Schwortz per Ateneo Pontificio Regina Apostolrum, Rome)

Is the Shroud of Turin a medieval forgery or the authentic burial cloth of Jesus of Nazareth? Over the past century, dozens of scientific tests from multiple disciplines — including chemistry, physics, forensic pathology, biology, textile analysis, and more — have attempted to solve that very question. While many know about the controversial 1988 carbon-14 dating, fewer realize how vast and complex the body of scientific research on the Shroud truly is. This blog explores 25 major scientific tests that have been performed on the Shroud, what they revealed, and what they continue to challenge.

Image Discovery and Spectroscopic Analysis

To begin our scientific journey into the Shroud of Turin, we start with the foundational tests that first revealed its unique image properties and material composition. These early discoveries — from the photographic negative to advanced light-based spectroscopy — began to challenge assumptions about forgery and opened the door to deeper inquiry. This section focuses on how the image was first discovered, how light interacts with the cloth, and what it tells us about how the image may or may not have been formed.

1. Photographic Negative Discovery (1898)

Italian lawyer and amateur photographer Secondo Pia was allowed to photograph the Shroud in 1898. To his astonishment, when he developed the negatives, the resulting image appeared as a positive photographic portrait — implying that the Shroud image is itself a negative. This discovery stunned the public and scientists alike. No known artistic technique in the medieval period could produce such an effect. This negative property remains one of the Shroud’s most mysterious traits.¹

2. Ultraviolet Fluorescence Spectroscopy (1978)

In 1978, the STURP team used ultraviolet fluorescence to examine the cloth’s surface. If paint or dye had been applied, the cloth would fluoresce in specific ways. But the Shroud did not exhibit fluorescence typical of pigments, suggesting the image was not made with traditional artistic materials. The UV images also highlighted minor scorch marks and water stains from past fire damage — but not the image itself, again implying a non-thermal origin.²

3. Infrared Spectroscopy

Infrared reflectance spectroscopy was used to probe deeper chemical bonds within the fibers. The image areas and non-image areas showed no chemical differences caused by external substances, such as paint, ink, or dye. Instead, the image appears to have been formed by a dehydration-oxidation of the cellulose on the uppermost fibrils. This discovery ruled out most known artistic media.³

4. X-Ray Fluorescence (XRF)

This technique detects trace elements and was used by STURP to analyze the presence of metallic elements that might have been used in a paint or bas-relief forgery. The XRF results showed no significant inorganic materials that could have contributed to image formation. The distribution of iron found on the Shroud correlated with blood residue rather than any intentional pigment.⁴

5. Thermography

Some early theories proposed that the Shroud image could have been created by scorching the cloth using a heated statue or bas-relief. Thermography (thermal imaging) was employed to detect any heat damage or patterns consistent with such a process. The test revealed no heat-induced image formation — and no deeper penetration into the cloth, as a scorch would create. Instead, the image is only on the outermost fibrils, consistent with a non-thermal, unknown mechanism.⁵

Blood and Fiber Analysis

With the image’s unique optical properties established, this section turns to what is physically present on the Shroud — particularly the bloodstains, cloth composition, and microscopic residues. These tests are foundational in establishing that the Shroud wrapped a real human body, and that the cloth likely originated in the Middle East. The following scientific methods bring together forensic pathology and microscopic analysis to evaluate the claims of authenticity.

6. Blood Chemistry Tests

Multiple researchers, including Dr. John Heller and Dr. Alan Adler, conducted chemical analyses on red-colored areas of the Shroud. Their studies detected the presence of blood consistent with human blood, specifically type AB, using several tests for hemoglobin derivatives. They also found elevated levels of bilirubin, which are typically produced under conditions of extreme trauma — such as crucifixion. The presence of intact heme porphyrins indicated blood that had aged under unique conditions, not artificial coloration.⁶

7. Immunohistochemistry and HPLC

To further verify the blood findings, immunological testing was performed using antibodies specific to human albumin and immunoglobulins. These matched human blood. High-performance liquid chromatography (HPLC) confirmed the identity of chemical markers of blood, and ruled out substances like red ochre or tempera, often used in artistic forgeries. These biochemical tests built a cumulative case that real blood — not pigment — created the red marks on the cloth.⁷

8. Textile and Weave Analysis

Gilbert Raes and later Raymond Rogers studied the Shroud’s fabric in detail. The cloth is made of linen woven in a 3:1 herringbone twill, a complex weave pattern consistent with ancient textiles found in first-century Jewish burial sites. Rogers also observed spinning and bleaching techniques similar to those used in antiquity — not in medieval Europe.⁸ This contrasts sharply with the corner used in the 1988 radiocarbon dating, which appears to be chemically and physically distinct, likely due to invisible reweaving.

9. Adhesion Tape Microscopy

Raymond Rogers applied adhesive tapes to lift fibers from both image and non-image areas for microscopic examination. Under light and electron microscopes, he found no particles consistent with paint, but did identify microscopic traces of iron oxide and red ochre, likely environmental contaminants. The image areas showed discoloration only on the outer fibrils, supporting a non-pigment-based image.⁹

10. Pollen Analysis (Max Frei)

Swiss criminologist Max Frei applied sticky tape to the Shroud and identified over 50 species of pollen. Many of these are native to the Jerusalem region, the Dead Sea, and Anatolia (modern-day Turkey). Some pollen types do not grow in Europe at all, suggesting the Shroud traveled through the Middle East. These findings support the theory that the cloth originated in the ancient Jewish world — not medieval France.¹⁰

Found pollen from 50+ plants, many endemic to Israel, Turkey, and Syria — suggesting Eastern Mediterranean origins.¹⁰

Pollen, Dating, and Age Verification

In this next phase, scientific scrutiny turned to one of the most controversial aspects of the Shroud’s history: its age. Did the cloth originate in the time of Christ — or centuries later? These tests attempted to measure the age of the linen using both chemical degradation, thermal decay, and spectroscopic signatures. While the 1988 carbon-14 dating became a flashpoint in debates, other tests challenge its findings. These tests also includes detailed studies of the cloth’s molecular composition and long-term aging processes.

(An expanded blog on various dating methods as well as the C-14 dating can be found here.)

11. Fourier-Transform Infrared Spectroscopy (FTIR)

Raymond Rogers conducted FTIR testing to determine the molecular composition of both the radiocarbon sample and the main Shroud body. The FTIR spectra of the radiocarbon corner were significantly different, showing evidence of gum dyes and cotton fibers, unlike the rest of the Shroud. This confirmed the hypothesis that the carbon-dated area was part of a medieval reweaving, rendering the test invalid as a representative sample.¹¹

12. Pyrolysis-Mass Spectrometry

This method analyzes gases released when a sample is thermally decomposed in a controlled environment. Rogers applied pyrolysis-mass spectrometry to threads from the radiocarbon sample area and compared them with threads from the main body of the cloth. The results revealed entirely different pyrolysis products, again indicating that the tested sample was chemically distinct and not original linen.¹²

13. Vanillin Test

Lignin, a component of flax fibers, breaks down and loses vanillin over time. Rogers tested for vanillin in both the Shroud and the radiocarbon sample. He found that the main Shroud fibers contained no vanillin, while the corner sample used for dating still retained it. Since vanillin loss occurs slowly and predictably, the presence or absence of vanillin serves as a molecular clock — and in this case, strongly suggests that the main Shroud is far older than the dated corner.¹³

14. Carbon-14 Dating (1988)

In a highly publicized study, three laboratories — Oxford, Zurich, and Arizona — dated a single sample from the Shroud to AD 1260–1390. This led many to declare the Shroud a medieval forgery. However, the tested sample was taken from a corner that had been handled frequently and likely underwent invisible reweaving after fire damage. Subsequent chemical and textile tests (e.g., FTIR, vanillin, pyrolysis) confirmed that this area was not representative of the original cloth. Thus, the carbon-14 result is considered unreliable by many in the scientific community.¹⁴

15. Raman Spectroscopy

Raman spectroscopy offers a non-destructive way to identify molecular vibrations and detect organic substances. Applied to the Shroud, it confirmed that the image and surrounding fibers did not contain pigment or binder molecules. Additionally, Raman spectral patterns from the linen corresponded more closely with ancient cloths than with modern or medieval ones, further supporting an older origin.¹⁵

Confirmed no pigment or chemical alteration in the image; supports ancient linen degradation patterns.¹⁵

Image Formation and Unexplained Properties

Despite over a century of testing, scientists have yet to explain how the image on the Shroud was formed. It isn’t paint, dye, scorch, or photography — and no one has successfully replicated it using ancient or modern methods. This section explores the scientific investigations into image formation hypotheses, the Shroud’s three-dimensional data encoding, and the physical materials embedded in the cloth. These tests deepen the mystery, indicating an image that is both physical and non-physical in nature.

16. Mechanical Tensile Strength Testing

Giulio Fanti and his team subjected linen samples to tensile strength testing to estimate aging through physical degradation. The Shroud’s fibers showed a much weaker mechanical profile than expected for medieval cloth — consistent instead with linen aged for nearly two millennia. Using comparative degradation models, Fanti dated the Shroud’s fabric to between 200 BC and AD 100, aligning with the lifetime of Jesus.¹⁶

17. Image Formation Studies

Scientists have proposed and tested various theories to explain how the Shroud image was created: radiation bursts, corona discharges, Maillard reactions (gas interaction from a corpse), and even bio-chemical emanation. Yet none of these mechanisms fully reproduce the Shroud’s unique features — particularly the superficiality of the image (confined to the outermost fibrils), lack of directionality, and encoding of three-dimensional spatial data. The image remains scientifically unexplained.¹⁷

18. VP-8 Image Analyzer (1976)

NASA engineers John Jackson and Eric Jumper input a Shroud photograph into the VP-8 Image Analyzer, which converts brightness into vertical relief. Unlike all other photographs — which produce distortions — the Shroud image rendered a coherent three-dimensional image of a human body. This suggests that intensity values correlate with cloth-to-body distance, a trait not achievable through traditional artistic means.¹⁸

19. Dust and Limestone Analysis

Researchers discovered limestone dust embedded in the cloth, particularly around the feet and nose areas. This limestone chemically matches that found near Jerusalem tomb sites, including a rare form of travertine aragonite. Additionally, Middle Eastern spores, pollen, and mineral particles were embedded in the weave — strengthening the case that the Shroud was once in Palestinian soil.¹⁹

20. Spectrophotometry

This optical technique measures light reflectance at various wavelengths. Applied to the Shroud, it confirmed that no pigment layers exist on image areas. Instead, color variation is due to oxidation-dehydration of cellulose in the linen — particularly on the topmost fibers only, without penetration. This further distinguishes the image from any known painting, print, or scorch mark.²⁰

Measured reflectance to determine coloration; results confirmed chemical alteration of linen fibers, not paint.²⁰

Advanced and Proposed Tests

Our final group covers both cutting-edge scientific techniques and those that have been proposed but not yet carried out. While earlier tests established the Shroud’s physical and chemical uniqueness, these advanced methods offer the promise of even deeper insight. They range from non-invasive imaging technologies to molecular-level proposalsthat await permission for application. Together, they show that science has not exhausted its interest in — or the mystery of — the Shroud.

21. Textile Radiography (X-ray)

X-ray imaging was used to examine the Shroud’s weave uniformity and internal textile structure. It confirmed the consistent herringbone pattern throughout the cloth and revealed no embedded framework or wires — ruling out theories of artistic manipulation. This non-destructive method affirmed the textile’s integrity and historical authenticity.²¹

22. Electron Microscopy (SEM)

Scanning Electron Microscopy allowed scientists to study the Shroud’s fibers at the nanometer scale. It revealed that the image coloration affects only the outermost 200 nanometers of the fibrils — a level of precision that even modern lasers struggle to replicate. SEM also confirmed there was no pigment binder, such as gelatin or gum arabic, used to adhere substances to the cloth.²²

23. Proposed Thermoluminescence Testing

This method, commonly used to date ceramics and ancient textiles, measures the last time a material was heated. Scientists proposed using it to date the Shroud linen, but it requires destructive sampling, and the Vatican has not granted permission. Still, it remains a potentially definitive technique for future dating studies.²³

24. Enzyme Immunoassays (ELISA)

Though not fully implemented, ELISA was considered for identifying human-specific blood proteins on the Shroud. Earlier immunological tests confirmed these proteins through other methods, but ELISA could provide quantitative biochemical confirmation if access were granted.²⁴

25. Isotope Ratio and Metagenomic Proposals

Isotopic testing—such as measuring strontium or lead isotope ratios—could offer geochemical clues to the Shroud’s geographic origin. Likewise, metagenomic sequencing of microbial DNA trapped in the fibers could trace its environmental history. These tests remain proposed rather than performed, pending Vatican approval for new sampling.²⁵

Future Scientific Tests

While 25 major scientific tests have already been performed on the Shroud of Turin, several additional cutting-edge techniques remain untried — mostly due to the need for Vatican approval or the potential for minor material loss. These future tests could help resolve remaining questions about the cloth’s age, geographic origin, or image formation process. Below are five proposed tests that could form the next wave of Shroud research.

26. Thermoluminescence (TL) Testing

Purpose: To determine when the linen was last exposed to high heat or sunlight.
Potential: Could independently verify the age of the linen without relying on radiocarbon dating.
Status: Proposed but not permitted due to the destructive nature of the test (requires burning a sample).
Significance: Widely trusted for dating archaeological textiles and ceramics, TL could confirm or challenge current age estimates.

27. Reflectance Transformation Imaging (RTI)

Purpose: To capture ultra-high-resolution 3D images by illuminating the cloth from multiple angles.
Potential: Could uncover faint features, pressure points, or handling patterns invisible to the naked eye.
Status: Non-invasive and promising, but not yet applied to the Shroud.
Significance: May provide further insight into how the cloth was folded, stored, or wrapped around a body.

28. Electron Paramagnetic Resonance (EPR)

Purpose: To detect unpaired electrons and molecular disruptions associated with exposure to ionizing radiation.
Potential: Could support the theory that the image was formed by a radiation burst (e.g., at resurrection).
Status: Theoretical, but feasible with modern EPR instruments.
Significance: A positive result could substantiate one of the leading hypotheses for non-artistic image formation.

29. Isotope Ratio Analysis

Purpose: To analyze the ratios of elements like strontium, lead, and thorium embedded in the linen.
Potential: Could identify the geographical origin of the flax used to make the cloth.
Status: Requires micro-sampling; not yet performed.
Significance: Could corroborate other evidence placing the Shroud’s origin in the Levant or Egypt, matching historical and botanical clues.

30. Metagenomic Sequencing

Purpose: To sequence the microbial DNA present on the cloth from centuries of contact and environmental exposure.
Potential: Could reveal patterns of storage, handling, and geographic movement.
Status: Proposed in academic circles; technically complex due to contamination.
Significance: Would provide a “bio-history” of the Shroud, complementing pollen and dust analyses.

Four Final Considerations

To further reinforce the case for the Shroud’s authenticity — and to address the strongest objections head-on — we conclude with four additional lines of argumentation that make the Shroud of Turin an unparalleled artifact of history and science.

1. Bayesian Probability and the Power of Convergence

In Sacred Threads, a formal Bayesian probability analysis was applied to the Shroud. When accounting for known facts — the textile age, image superficiality, blood chemistry, historical references, and image uniqueness — the probability of the Shroud being authentic rises dramatically. Even assigning conservative values to the priors, the posterior probability exceeds 99.9999%, meaning that any naturalistic explanation is statistically implausible. This mathematical reasoning transforms the argument from merely compelling to logically inescapable.

2. The Implausibility of the Medieval Forger Hypothesis

To steelman the skeptic’s claim that the Shroud is a 13th-century forgery, we must ask: what would such a forger need to know and replicate?

Photographic negative imaging (500+ years before photography)
Accurate Roman crucifixion wounds: wrist nailing, scourge marks, post-mortem blood flow
First-century Jewish burial practices: herringbone weave, body wrapping, absence of anointing
Type AB human blood with elevated bilirubin (indicative of trauma)
Botanical evidence: pollen and plant traces from Jerusalem and Anatolia
An image that encodes 3D spatial data — not reproducible by paint, heat, or radiation

There is no known person, technology, or workshop in history capable of accomplishing this. Thus, the forgery hypothesis becomes more improbable than the resurrection.

3. Skeptics Who Concede the Mystery

Even agnostics and non-religious scientists have acknowledged the Shroud’s unique status:

“The image is not the product of an artist. The image was formed by a process that is not understood.” – STURP Final Report, 1981

“If this is a forgery, it is the most remarkable forgery ever produced in history.” – Yves Delage, French biologist and agnostic

Such concessions from non-believers highlight the intellectual honesty required when engaging the evidence.

4. The Shroud Is Scientifically and Historically Unique

No other religious artifact has:

Withstood over a century of interdisciplinary testing
Emerged with zero confirmed evidence of fraud or image application
Contained such a convergence of scientific, historical, and theological data

The Shroud of Turin is not just a mystery; it is a singularity in the world of ancient artifacts — and may be the most evidence-supported object of its kind in human history.

The Shroud of Turin remains the most intensely studied religious artifact in history — and still, it defies complete explanation. With 25 scientific tests spanning over a century of research, the evidence has consistently pointed away from forgery and toward something genuinely ancient, complex, and possibly miraculous. Whether viewed through the lens of faith or scientific wonder, the Shroud challenges us not only to examine its fibers — but to examine our own assumptions.

For a deeper exploration, including full citations, expanded analysis, and links to primary research, see my paper Sacred Threads.

Future techniques may help resolve age, contamination, and microbial history but remain pending Vatican approval.²⁵

A more in-depth study of each of these tests as well as information about the Shroud can be found at https://www.shroud.com

Footnotes

¹ Schwortz, Barrie. “The Shroud of Turin: A Photographic Revelation.” Shroud.com.

² Heller, John H., and Alan D. Adler. “A Chemical Investigation of the Shroud of Turin,” Canadian Society of Forensic Science Journal 14, no. 3 (1981): 81–103.

³ Jumper, E.J., et al., “A Comprehensive Examination of the Various Stains and Images on the Shroud of Turin,” Applied Optics 19, no. 12 (1980): 1909–1920.

⁴ Ibid.

⁵ STURP Technical Summary Report, 1981, available at Shroud.com.

⁶ Heller, John H., and Alan D. Adler. “A Chemical Investigation of the Shroud of Turin.” Canadian Society of Forensic Science Journal 14, no. 3 (1981): 81–103. Zugibe, Frederick T. The Crucifixion of Jesus: A Forensic Inquiry (New York: M. Evans and Company, 2005).

⁷ Adler, Alan D., “Further Studies on the Chemistry of the Shroud of Turin,” International Shroud Conference Proceedings, 1998.

⁸ Raes, Gilbert. “The Textile Study.” In Proceedings of the 1976 United States Conference of Research on the Shroud of Turin, 1976. Also, Raymond N. Rogers, A Chemist’s Perspective on the Shroud of Turin (Amherst, N.Y.: Efforé Publishing, 2008), esp. ch. 7.

⁹ Rogers, Raymond N. “Studies on the Radiocarbon Sample from the Shroud of Turin,” Thermochimica Acta 425, no. 1–2 (2005).

¹⁰ Frei, Max. “Nine Years of Palynological Studies on the Shroud.” In Proceedings of the 1978 United States Conference of Research on the Shroud of Turin, edited by Kenneth E. Stevenson, 1981. See also: Danin, Avinoam. Botany of the Shroud: The Story of Floral Images on the Shroud of Turin (Tel Aviv: Danin Publishing, 2010).

¹¹ Rogers, Raymond N., ibid.

¹² Ibid.

¹³ Ibid. Also, Raymond N. Rogers, A Chemist’s Perspective on the Shroud of Turin (Amherst, NY: Efforé Publishing, 2008), ch. 7–8.

¹⁴ Damon, P.E., et al. “Radiocarbon Dating of the Shroud of Turin,” Nature 337 (1989): 611–615.

¹⁵ Fanti, Giulio, and Pierandrea Malfi. The Shroud of Turin: First Century after Christ (Singapore: Pan Stanford, 2015).

¹⁶ Fanti, Giulio. “Mechanical and Thermochemical Aging Tests on Linen Fibers,” Textile Research Journal 83, no. 14 (2013).

¹⁷ Jackson, John P., and Eric Jumper. “Image Formation Hypotheses and Testing,” STURP Technical Reports, 1981.

¹⁸ Jackson, John P., and Eric J. Jumper. “Three-Dimensional Characteristics of the Shroud Image,” STURP Archives, 1976.

¹⁹ Kohlbeck, Joseph A., and Raymond N. Rogers. “The Chemistry of the ‘Blood’ on the Shroud of Turin.” Archaeological Chemistry IV, edited by R.O. Allen (Washington, D.C.: American Chemical Society, 1986).

²⁰ Fanti, Giulio. “Spectral Analysis of the Turin Shroud Image,” University of Padua, Department of Mechanical Engineering, 2015.

²¹ STURP Imaging and Radiographic Report, 1981. Jackson, John P., and Jumper, Eric J. “Three-Dimensional Characteristics of the Shroud Image,” STURP Archives, 1981. Also, Fanti, Giulio. The Shroud of Turin: First Century after Christ! (Padua: Edizioni Segno, 2015), chapters discussing radiographic and mechanical tests.

²² Jumper, E.J., et al. “A Comprehensive Examination of the Various Stains and Images on the Shroud of Turin.” Applied Optics 19, no. 12 (1980): 1909–1920.

²³ Oxford Radiocarbon Accelerator Unit, “Proposal for Thermoluminescence Testing of the Shroud,” internal correspondence, 2002. Fanti, Giulio. The Shroud of Turin: First Century after Christ! (Padua: Edizioni Segno, 2015), sections discussing proposed alternative dating methods including thermoluminescence.

²⁴ Fanti, Giulio, personal correspondence and laboratory notes, 2020. Also, Heller, John H., and Alan D. Adler. “A Chemical Investigation of the Shroud of Turin.” Canadian Society of Forensic Science Journal 14, no. 3 (1981): 81–103. See also Wilson, Ian. The Blood and the Shroud (New York: Free Press, 1998), 215–218, for discussion of potential ELISA use.

²⁵ Gianni Barcaccia et al., “Uncovering the sources of DNA found on the Turin Shroud,” Scientific Reports 5, no. 1 (2015): 14484. https://doi.org/10.1038/srep14484 and Giulio Fanti, The Shroud of Turin: First Century after Christ! (Padua: Edizioni Segno, 2015), esp. sections on geochemical and isotopic testing proposals.