Welcome to Bortolot Daybreak
DAYBREAK ARCHAEOMETRY SERVICES
News notes and topical warnings
Should you be concerned about artificial irradiation of objects? (a lot of rumors, but the answer is: not really!)
Worries about irradiation of mail
Daybreak is the only commercial laboratory in the Americas providing thermoluminescence (TL) dating of ceramic art objects for the purpose of authentication. TL is a radiation dose measurement technique that has proven highly successful over the past 30 years for determining whether pottery (or the cores from metal castings) were fired in antiquity or recently. We have been involved with this field as a company for 25 years and our laboratory directory has been active in luminescence dating for 30 years. Please browse through the topics to the left for further information; they should answer most of your immediate questions. Should you need more information, or wish to consult about the applicability of TL to an object, please contact us. Consultation is important, as ceramics from some areas are difficult or impossible to date by TL, or the date might be misleading due to forgers' activities.
We limit ourselves to authenticity dating. While we get many requests for archaeological dating (which requires considerable additional work to reduce the uncertainty of the dates), we generally cannot accommodate them, due to limited time resources. We would be happy to suggest certain university labs which might be able to work with you.
We specialize in TL dating only as our parent company, Daybreak Nuclear, is a leading manufacturer of the measurement instruments and software for this field, and do not offer any other analytical services.
We welcome your comments and suggestions. Please contact
us if you find any topic confusing or missing.
last updated February 4, 2003
Some of these new topics will eventually have their own pages, or will be incorporated into the FAQs
DAYBREAK’S OFFICES AND LABORATORY HAVE MOVED
Daybreak has moved its offices and laboratory to a new commercial
in Branford, CT, about 4 miles from its Guilford home, easy to get to
I-95. We are retaining our mailing address and production
in Guilford. The phone and fax numbers remain the same, but we
you to call us at the direct phone line in Branford +1 (203)
Easy directions to reach us are in the VISITING
DAYBREAK page. Office hours for sample taking are by
BE CAREFUL OF CHINESE ‘ANTIQUITIES’ AND TL REPORTS FROM HONG KONG (Seattle Times investigation)
(February 3, 2003) An on-going investigation by the Seattle
into fraud in some galleries selling Chinese antiquities has resulted
a series of articles published January 26-29, 2003. The majority
of objects in one Seattle shop were judged by experts to be
and two (one reputedly T’ang; the other Ming) were purchased by a
undercover because they had TL test reports from two Hong Kong TL
asserting that the TL ages were consistent with the periods
These two objects were sent both to Daybreak and to Oxford
Ltd., and found to be modern. The complete story is to be found
One of the Hong Kong laboratories appears to be owned or at least
by a principal of the shop investigated. As with some other
TL laboratories, nothing is known about the identity or experience of
doing the analyses in this lab, and in fact they are not located at the
address on their reports, or locatable at all.
ALERT!! DISHONEST DEALER CAUGHT ALTERING DAYBREAK REPORTS AND JAILED. PROBLEM MORE WIDESPREAD THAN PREVIOUSLY THOUGHT.
New York (October 21, 2002) Mourtala Diop, a dealer in African art for many years in New York and in Europe, has been charged by police in New York City with grand larceny and forgery and jailed for selling fraudulent Nigerian ceramic sculptures using altered Daybreak TL reports. He is being held in lieu of US$ 100,000 bail. The New York City grand jury has held him over for trial. A civil suit for restitution in the neighborhood of US$ 240,000 has also been filed against him in federal court. Additional instances of sales of problematic terra cotta by him and by others using forged reports are coming to light as a result of this news. We had heard of an instance of this in August 2001, and posted a warning on the Bortolot Daybreak web site at that time. All the objects so far involved were TL-dated by us in 2000 and later. Some samples were taken by Daybreak, others by our designated sample-takers. Certain of these objects were made of unrelated fragments, some containing an ancient fragment (though not necessarily from anything resembling the present object!) with the rest being modern pottery or a mixture of ground pottery and glue. In all these cases, comments prejudicial to the object—that samples contained resins, or were modern, or were of differing clay, and that the object should be examined by an experienced conservator—were removed, and in every case where Daybreak had not taken samples, the name of the sample-taker was altered to state that Victor Bortolot had examined the object and taken the samples himself.
Update (January 17, 2003) Mr. Diop made bail and has fled the country taking the contents of his apartment (which reportedly contained several hundred objects) with him.
We urge anyone with Nok and Ife objects sold to them with our
to contact us for confirmation that their report is as we issued
All Nok (especially complete figures) and Ife objects purchased from
on should be scrutinized carefully, as the problems all too common now
started some years ago, and early on no one was looking at them as
as we do today.
COLLECT RESPONSIBLY—LEARN ABOUT U.S. REGULATIONS ABOUT LEGALITY OF ART OBJECTS AND IMPORTATION
As many of you may know, it is illegal to import antiquities from certain countries into the United States. Often the regulations have gone into effect on a certain date, and anything known to have left the country of origin before that is perfectly legal to own, buy, sell, or ship anywhere. This generally has meant that sales of newly excavated objects from Mexico, the Classical Area, and some other places are forbidden here. In many developing countries there is a prohibition against export of antiquities but no corresponding bans on importation or ownership elsewhere, so there is a legal trade here and in Europe. It is a complex patchwork that changes with time, but fortunately all the information you need is available on a well-designed web site run by the U.S. Department of State at http://exchanges.state.gov/education/culprop/ . There is a useful pamphlet from the U.S. Customs Service about how to import art, with information about what is dutiable and what is not; a .pdf file you can view or print out is available at http://www.cbp.gov/ImageCache/cgov/content/laws/informed_5fcompliance_5fregs/icp061_2epdf/v1/icp061.pdf . It is important to declare everything on entry to the U.S. even if perfectly legal and non-dutiable.
Because of the change of regulations with time, you should document
the purchase date of any antiquity by a detailed bill of sale, an
at that time, or such independent proof of its being in the U.S. as a
test report or other document. The U.S. does not enforce such
retroactively, so that anything purchased legally will remain
For presently proscribed objects it is important that you exercise due
diligence by obtaining proof that they were imported before the ban
into effect. Otherwise it may prove impossible to sell publicly,
and leave you open to possible confiscation or a nasty and expensive
with customs officials.
PROBLEMS WITH NIGERIAN TERRA COTTAS AND BRONZES
Nigerian antiquities include some of the most sought-after and expensive African art. Thus there is the most incentive to perpetrate fraud. The types most troublesome are Nok and Ife terra cottas and Benin bronzes.
Nok ceramics were at one time exceedingly rare on the market and until late 1993 were almost always fragments in poor condition—chance finds washed out of riverbanks. Virtually all objects said to be Nok were easily discernable fakes, the originals being so uncommon that fakers could only copy illustrations out of books. A consortium of European dealers is said to have organized systematic clandestine excavation in the Nok area in 1993, involving many hundreds of diggers. As a result, there suddenly appeared on the market a flood of genuine, magnificent Nok heads, and the fakes all but disappeared. We wondered then whether these objects were made as heads only, since no (or very few) complete figures were presented for sale here. A few years later large complete figures did make their appearance. There was inevitably some restoration since the pottery is very low-fired, and therefore quite fragile. By 1997 it became evident that many of these were restored beyond acceptable limits. We were finding objects with mismatched heads and bodies, missing areas replaced with unrelated fragments, and extensive (sometimes 100 per cent!) reconstruction using a mixture of dirt or pottery powder and a binder. Large missing areas may be replaced with modern pottery, and sometimes a completely modern object may have ancient pottery fragments embedded in the areas most likely to be sampled for TL. We have also seen very unlikely assemblages of genuine small figures into a larger whole, usually attached to an upturned pot. The surface of all these objects is often covered completely with a fine-grained mud with a paint vehicle to obscure the repair/reconstruction, making examination difficult. We now are taking more samples from an object, sometimes as many as twelve for a large figure, in an effort to find differences in clay type, as well as the TL age. Visual examination is very important, as it usually shows the differences in clay color and the size, quality, and quantity of the grog generally found in this pottery. These differences may not be evident in the TL measurements, or samples visually similar may appear to be quite different in their TL characteristics. Scraping away small areas of the surface may be necessary to see the clay body. We also probe for areas of restoration. When we do the TL measurements we do screen for the presence of synthetic binders, as restored areas may be sampled despite efforts to avoid them. When binder material is found in a sample it is reported.
It has been mentioned that this pottery is very low fired and extremely fragile. A certain amount of restoration is expected, especially with figures, and is acceptable. The level of restoration tolerated is a matter of individual taste, but certainly all major portions of a sculpture that give it its character must be original, with only minor repair.
We take a “devil’s advocate” role in examining objects: we look for problems. It is not that we want the object to have flaws, but that we wish to keep the market as free as possible of problem pieces. This is to the benefit of everyone in the long run, even if it may sometimes prove a great disappointment for the seller. It protects the buyer and helps forestall the general attitude, “It’s all fake!”, that has poisoned the market for certain classes of objects.
Other Northern Nigerian pottery, from the Sokoto and Katsina regions, contemporary with Nok, came onto the market a couple of years after the great flood of Nok, but is now less commonly seen.
Ife terra cottas, mostly beautifully modeled heads, are very scarce. We have been seeing many fraudulent heads and heads-plus-torsos. We tell people that because of this rarity, Ife is likely to be either fake or stolen. Starting about 4-5 years ago, these objects started to appear in quantity, and initially were all modern ceramic. Then objects appeared that were made of ancient pottery. Fortunately, in most cases Nok and other 2000 year old Nigerian pottery fragments and powder were used, and it was easy to distinguish from the 500-700 year old Ife pottery. Now, Ife fakes are fabricated out of more age-suitable material, but they are still easily detected by the experienced eye and a few simple tests. One especially clever attempt modeled an Ife face on a small Katsina head. The head proved to be 2000 years old, and the face was a mixture of pottery powder and resin. Sometimes an ‘Ife’ head with a hat is seen. The hat may be the bottom and foot ring of a pot, and the face a resin mixture.
Fabrications of this sort are sometimes seen in Kalabar grave markers (a head or human figure atop an upturned pot) and Bura objects from Niger.
Benin bronzes are a particularly thorny issue. The bronze
brass) itself is not datable. Though analysis of the alloy may
conformity with what is known to have been used in a certain period, it
is no proof that the metal alloy was not made in the present according
to the proper recipe. Dating from patina and corrosion products
very difficult. The only absolute dating technique possible is TL
dating of a casting core, if it is present, as it would have been
at the time of casting. Unfortunately, it is often difficult to
if the core material actually belongs to the casting. We have
so many cases where old core (or artificial core) has been introduced
new bronzes that we generally will no longer date any Nigerian bronze
On a case-by-case basis, we may decide to date floating cores, where
core is completely surrounded by metal. There still is the
that any TL date for the core may not be applicable to the bronze
CONFUSION: DOES TL DATING ESTABLISH AUTHENTICITY?
The short answer is: not really, at least not by itself. In a
perfect world, an object might be authentic or might be a reproduction,
but there would be no attempt to circumvent scientific analysis with
using ancient material in a new object. The TL result then would
indeed correspond with authenticity, pro or con. Years ago this
was the case. In real life nowadays, all TL can do is determine
long ago particular fragments of pottery were fired, but can say
by itself about the piece in its entirety. The term ’authenticity
dating’ is a relic of the early days of TL dating in the late 60’s and
early 70’s. At that time the term was meant to describe dating
less rigorous than archaeological dating. For archaeology,
a dozen sherds from an context would be dated (and the dates averaged);
considerable time and effort is expended to achieve the least
in the TL age. Art objects must be dated using much smaller
and there is no access to the burial site: many of the parameters that
enter the age calculation are estimated since they cannot be measured
are too time-consuming to be practical. ‘Authenticity TL dating’
is simply ‘archaeological TL dating’ with uncertainties of about 25 per
cent rather than below 10 per cent, and is usually done for the purpose
of providing evidence for or against an object’s authenticity in
with other expertise. It is improper to use TL as the sole
of authenticity. Imagine a statue of Mickey Mouse ™ carved out of
a 2000-year-old Roman brick: it is not a 2000-year-old Roman statue,
the TL age will be 2000 years!
THE RIGHT WAY TO ESTABLISH AUTHENTICITY— TL IS ONE FOOT OF THE TRIPOD
As you can see from the paragraphs above, TL is not as useful as it formerly was in establishing authenticity. Other means are necessary to determine whether the TL age may be applied to the object as a whole. We have always stressed this, but many people want the simple ‘magic bullet’ to guide them, and have used TL dating far beyond what it really determines—the age of the sample.
A definition of the authenticator’s role is to prove an object genuine or to have an undisputed origin by the examination of factual information, physical evidence, collection history, and well-researched opinions. The authenticator expert must be recognized as an authority and should be willing to serve as an expert in a legal proceeding; he or she may be an art historian, appraiser, or dealer, or some other with an acknowledged expertise in the material under scrutiny —and not all such people are qualified as an authenticator in the formal, legal sense. The expert looks at style, iconography, and construction, and calls on the conservator’s examination to look at details of materials and repairs (and to make the condition report for later use in an appraisal); the expert and conservator may call for such scientific expertise as necessary to confirm or dispute their hypotheses. The expert and conservator both are needed in addition to any scientific analyses, if one is to attempt to truly authenticate an object. This is of course more expensive, and the more subjective opinions of the authenticator may be disputed by other experts, but one will have a surer basis on which to form a judgment. Generally TL should be the final step, once the authenticator and conservator have made their examination; then there will be enough information to make a decision. The increasingly widespread use of ancient materials in the manufacture of fakes makes this order of examination prudent. It may be that the collector or dealer who has TL dates done is sufficiently experienced and capable to perform the offices of expert and conservator in an informal way, but it is best to enlist the aid of a ‘committee’—sometimes a single person can miss a significant clue. Our laboratory director, Victor Bortolot, has considerable experience with African terra cottas, but while knowledgeable, he is not professionally qualified as an art historian/expert or conservator, and he will never estimate a value, and cannot issue a formal condition report. His comments made while examining objects are meant to be informative and should be useful, but are not intended in any way as definitive, and are not included in the scientific report unless the analyses indicate problems. The TL report is not to be regarded in any way as a condition report and will not detail areas where restoration was found, unless they are areas actually sampled. Because of the problems detailed above, there is often an advisory comment with regard to large Nok figures that they should be examined by the art historian and conservator in order to establish that the parts truly belong together. This is not based on suspicions, but on simple prudence, given the prevalence of fakery and over-restoration. If condition reports and appraisals are required, we can recommend people experienced with this material. We usually work as a team.
It should be noted that the condition of an object, as well as
qualities, rarity and age, is a very important determiner of an
value. A figure with a face so damaged that it is heavily
no matter how well, may have only one-third the market value of one
a face in good condition. A figure with a mismatched head and
may be worth more as separate pieces.
AN APPRAISAL IS NOT THE SAME AS CERTIFICATION OF AUTHENTICITY
As mentioned above, an appraiser may or may not be an expert
to authenticate an object. His role as appraiser is only to put a
value on the object, after authenticity has been established. The
appraiser should have a proper condition report from a conservator, as
the value is heavily dependent on the condition of an object. A
summary of what a proper appraisal report should contain may be found
NEW SECURITY MEASURES FOR DAYBREAK TL REPORTS
(January 17, 2003) The recent instances of forged and altered Daybreak TL reports have caused us to look into means of increasing the security of our reports. As of mid-January we have started to use a new report form on custom watermarked paper that will contain a custom holographic label with secure features and a frangible adhesive that will destroy the hologram if any attempt is made to remove it in order to affix it to a forgery. The embossed laboratory seal must also be present. There will be language on the report to the effect that only an original report is to be considered valid, and that the original must have the hologram and seal. To those who have been waiting patiently for their reports to be issued on the new forms, we are working through the backlog, and you will have them shortly
Those persons having reports issued in the past and wishing to have
them checked by us against our file copies and the new security
affixed will be able to do so. There will be a processing charge
of US$15 per report. A new secure report could be issued for a
FEES FOR EXAMINATION OF OBJECTS
Our general fee for examination of collections is US$ 150 per hour,
or US$ 250 per hour if pertaining to a legal case, civil or
No further charge is made for sampling when TL dating is to be
The fee for expert testimony during depositions or trials is also US$
per hour. Travel time is charged at a rate of US$ 50 per
When air travel is involved, an 8-hour day minimum must be charged.
PRICE INCREASE AS OF 2/15/03
Because of the cost of the new security features and the greatly
time now spent in examining objects, we are having to increase
prices a bit as of 2/15/03. Basically we are adding US$ 15-20 to
the former price structure and charging US$ 35 per object to examine
sample. Thus the total fee for an object we sample is $340.
are available at five objects and up.) We will charge US$
when one of our sample takers (whom you pay separately) provides the
to us. We will also be more likely to charge extra when more than
two samples are necessary. When we travel to take samples, an
charge per object sampled will be assessed in addition to travel
See our FAQ for details. Just
in case you are suffering from 'sticker-shock' from these prices, bear
in mind that when we started out doing TL dating commercially in 1972,
we charged $150 per test. In today's dollars, this is about
In fact, since 1994, we have not kept up with inflation, and due to
vigilance lately, we actually are spending more time on each object.
SHOULD YOU MAIL OBJECTS OR SAMPLES?
In the aftermath of the anthrax bioterrorism, the US Postal Service has been starting to implement electron beam sterilization of mail. At present, according to a report on January 11, 2002 in The New York Times, only mail to federal recipients and some media companies are being treated, some it generally should not be a concern. We are concerned, of course, since a radiation dose lethal to micro-organisms is equivalent to thousands of years' dose to pottery, and would completely destroy the dose information carried in the pottery. This would render it unusable for TL dating.
While the chance of this happening now is remote, we are recommending that objects and samples be sent by FEDEX or UPS. Since this problem affects many commodities sent by mail, such as unprocessed film, photographs, semiconductors (memory cards, etc.), and even food, we expect that there will be some means developed to prevent irradiation (special class of mail?). For more information on the impact of irradiation on museum and research materials, see the Smithsonian Institution website at http://www.si.edu/scmre/about/mail_irradiation.htm
In recent weeks there have been several instances where our TL reports have been copied with alterations, to omit the SPECIAL COMMENTS section. These cases are all reports about Nok figures. The comments stated that the sampled areas were of different clays, and that the various parts of the object probably did not belong together. Reports are sometimes furnished to possible buyers without the photos, which carry a signed synopsis of the report on a label. You will have no assurance that the object is the one referred to in the report without the photo. Our reports are typewritten on forms printed in dark gray ink on gray laid paper, with an embossed laboratory stamp and the signature of our lab director, V.J. Bortolot. We urge you to call us for confirmation when offered an object with copied or suspicious papers, or insist on original reports or certified copies. If you furnish us with an image, we can match it to our file photo.
Thank you for visiting our site.