Testing Method of Pressed and Toughened (Specially Tempered) Glassware, 55811-55816 [2010-22826]

Agencies

• DEPARTMENT OF HOMELAND SECURITY
• Customs and Border Protection

[Federal Register Volume 75, Number 177 (Tuesday, September 14, 2010)]
[Notices]
[Pages 55811-55816]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-22826]


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DEPARTMENT OF HOMELAND SECURITY

Customs and Border Protection

[Docket No. USCBP-2007-0099; CBP Dec. 10-31]


Testing Method of Pressed and Toughened (Specially Tempered) 
Glassware

AGENCY: U.S. Customs and Border Protection, Department of Homeland 
Security.

ACTION: Notice of method CBP uses to test pressed and toughened 
(specially tempered) glassware for tariff classification purposes.

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SUMMARY: This document adopts modifications to the test method 
currently applied by U.S. Customs and Border Protection (``CBP'') for 
the testing of pressed and toughened (specially tempered) glassware, as 
set forth in Treasury Decision (T.D.) 94-26 which was published in the 
Federal Register on March 22, 1994. This document sets forth revised 
criteria for interpreting the results obtained from the cutting test 
for opaque glassware and provides an interpretation of breakage for 
that test. In addition, this document reinstates a previously used 
testing method, the center punch test, and provides a

[[Page 55812]]

description of the center punch apparatus to be used for that test. The 
final CBP test method for pressed and toughened (specially tempered) 
glassware for tariff classification purposes is set forth in its 
entirety in this document.

DATES: CBP will begin applying this revised test method on glassware 
entered, or withdrawn from warehouse, for consumption effective October 
14, 2010.

FOR FURTHER INFORMATION CONTACT: Margaret Chinn, Office of Information 
and Technology, Laboratories and Scientific Services, (202) 344-1566; 
Stephen Cassata, Office of Information and Technology, Laboratories and 
Scientific Services, (202) 344-1309.

SUPPLEMENTARY INFORMATION: 

Background

    This document sets forth modifications to the criteria utilized by 
U.S. Customs and Border Protection (``CBP'') to test certain glassware 
articles to determine whether they are ``pressed and toughened 
(specially tempered)'' for tariff classification purposes under the 
Harmonized Tariff Schedule of the United States (``HTSUS''). The 
glassware articles subject to these testing procedures are generally 
imported into the United States under subheadings 7013.28.05, 
7013.37.05, 7013.42.10, 7013.49.10, and 7013.99.20, HTSUS. Articles of 
``safety glass, consisting of toughened (tempered) or laminated glass'' 
that are normally imported under heading 7007, HTSUS (e.g., 
architectural plate glass and vehicle windshields), are not within the 
purview of this final notice.
    Information regarding the apparatus used, glass sample preparation, 
and the methods employed by CBP to test glassware articles to determine 
whether they are pressed and toughened (specially tempered) was 
previously set forth in the Federal Register (59 FR 13531, March 22, 
1994; see also, 59 FR 16895, April 8, 1994, correcting ``T.D. 94-25'' 
to ``T.D. 94-26''). Under T.D. 94-26, photographic equipment, 
polariscopes, tile saws (or similar table-mounted circular saws), or 
other apparatus and supplies, such as calipers, ovens, and water baths, 
can be used to test subject glassware articles. With respect to sample 
preparation, T.D. 94-26 states that a representative number of samples 
should be analyzed but recognizes the possibility that only one sample 
may be available for testing.
    The method to be used for the testing of pressed and toughened 
(specially tempered) glassware under T.D. 94-26 consists of three 
tests. They are the ``macroscopic analysis,'' ``thermal shock test,'' 
and ``evaluation of temper.'' The evaluation of temper test consists of 
a polariscopic examination for transparent or translucent glassware and 
a cutting test for opaque glassware. The proposed modification of the 
test method was limited to the cutting test for opaque glassware.

Proposed Modifications

    On January 9, 2008, CBP published a notice in the Federal Register 
(73 FR 1640) which proposed modifications to the method applied for the 
testing of pressed and toughened (specially tempered) glassware as set 
forth in T.D. 94-26 and solicited public comments. The notice proposed 
modifications to the cutting test for opaque glassware but did not 
propose changes to the testing procedures used for the macroscopic 
analysis test, thermal shock test, and polariscopic examination aspect 
of the evaluation of temper test. The notice also proposed to reinstate 
the ``center punch test'' and provided a description of the center 
punch apparatus that would be used for the proposed test. Finally, the 
notice proposed to allow for the optional use of additional tests by 
CBP that would be used only to verify the results obtained from the 
other testing procedures. The modifications set forth in the January 9, 
2008, notice are described in greater detail below.

Proposed Changes to Cutting Test for Opaque Glassware

    The cutting test for opaque glassware is used for opaque glassware 
and translucent glassware that cannot be examined polariscopically 
because they do not transmit adequate polarized light. In the notice of 
January 9, 2008, it was proposed to revise the criteria used to 
interpret the results obtained from the cutting test for opaque 
glassware. In addition, it was proposed to add an interpretation of 
breakage in the test because the guidelines set forth in T.D. 94-26 did 
not clearly explain how breakage should be interpreted. Under the 
proposal, CBP would interpret the test such that the presence of 
``some'' dicing or crazing would be sufficient to determine that a 
glass article has been specially tempered for tariff classification 
purposes. Under this standard, ``some'' would be considered to be any 
diced, crazed (gravel that remains tenuously in contact with 
neighboring pieces), or graveled (presence of small cubes of 
approximately equal dimensions on all six sides) fragment yielded from 
the cut sample that is more than just a fugitive diced, crazed, or 
graveled fragment. In addition, it was proposed to remove the 
references to tempered soda lime, borosilicate, and fluorosilicate 
glass that are currently in the test because the composition of the 
glass is not relevant for testing purposes.

Proposal to Add Center Punch Test

    The notice of January 9, 2008, also proposed to reinstate the 
center punch test. It was noted in the proposal that it is dangerous 
for an analyst to perform the cutting test on a sample that is less 
than five inches in diameter or five inches wide and that it would be 
preferable to use the center punch test in these cases. The center 
punch apparatus to be used to perform the test would be a slender tool 
approximately 8 to 12 inches in length with one end tapered to a point. 
The tool would be long enough to allow for its insertion into tall-form 
tumblers and other articles of similar shape while permitting the 
nonpointed end to extend above the rim. This would be necessary for 
handling and safety purposes when performing the center punch test. The 
pointed end of the center punch would not be so sharp so as to chip the 
glassware on contact without applying pressure.
    In order to perform the center punch test under the proposal, a 
sample would initially be set on a solid and level surface. An analyst 
would then place the pointed end of the center punch vertically against 
the inside center bottom or heel of the article. The analyst would 
strike the dull end of the punch with a hammer, using blows of 
gradually increasing severity until breakage occurs. The breakage 
pattern, approximate number, and relative shape and size of the 
fragments would then be noted. Thereafter, the breakage pattern and/or 
typical fragments would be photographed. It would only be necessary for 
the broken sample to exhibit ``some'' dicing, crazing, or graveling in 
order to be considered tempered for CBP's classification purposes. 
``Some'' would be considered to be any diced, crazed, or graveled 
fragments yielded by the broken sample that are more than just fugitive 
diced, crazed, or graveled fragments.

Proposal to Add Option to Use Additional Tests

    In addition, the notice of January 9, 2008, proposed to provide for 
the optional use of additional tests by CBP. The additional tests would 
be used by CBP only to verify the results obtained from the other 
testing procedures. It was stated that the additional tests would 
facilitate the overall testing process by ensuring that the results 
obtained from

[[Page 55813]]

the other testing procedures are accurate.

Discussion of Comments

    Comments were solicited in the notice of January 9, 2008, and the 
comment period closed on March 17, 2008. One commenter responded during 
this time period on behalf of two clients, a manufacturer and separate 
importer of tempered glassware. The commenter submitted two letters, a 
set of photographs, and a series of ten short videos. A description of 
the comments and other material in the submission, as well as CBP's 
related analysis, follows.

Comment:

    The commenter asserts that the standard proposed for the testing of 
pressed and toughened (specially tempered) glassware set forth in the 
notice of January 9, 2008, would produce erroneous results and would 
not meet certain parameters established by the courts for testing 
methodology.

CBP's Response:

    The commenter submitted photographs and videos in an attempt to 
demonstrate that CBP's proposed testing method for the testing of 
pressed and toughened (specially tempered) glassware would produce 
erroneous results. As discussed further below, however, CBP does not 
find the commenter's submission persuasive in this regard because the 
proposed modifications to the testing method would actually introduce a 
higher degree of accuracy into the testing process. In addition, CBP 
believes that this testing method would withstand judicial scrutiny 
because the generally accepted methods in the standard are accurate, 
testable, and have been subject to peer review and publication.

Comment:

    The commenter states that the center punch test is not a useful or 
reliable test for tempered glassware and opposes its reinstatement by 
CBP. The commenter expressed its concern that CBP did not make clear in 
the notice of January 9, 2008, whether the center punch test would be 
used in lieu of, or in addition to, the cutting test. Moreover, if the 
center punch is intended to be used in addition to the cutting test, 
the commenter questions the relative weight CBP will assign to each 
test in determining whether an item is considered tempered.

CBP's Response:

    CBP's position is that the center punch test is useful and 
reliable, and CBP has determined that its reinstatement into the method 
for the testing of pressed and toughened (specially tempered) glassware 
is necessary. In support of this determination, CBP recognizes that the 
reinstatement of the center punch test will provide CBP analysts with a 
test that can be used in cases where the cutting test yields 
inconclusive results or when it would be dangerous to use the cutting 
test because of the dimensions of the sample.
    As noted above, one instance where the center punch test will be 
used is when the cutting test yields inconclusive results. In this 
situation, the results of the center punch test will be interpreted in 
conjunction with the results of the cutting test in order to make the 
correct classification determination. CBP believes this additional test 
is required because the CBP Laboratory occasionally tests samples that 
break into several large pieces when subjected to the cutting test. 
Without the benefit of a second test to confirm whether the tested 
glassware is actually pressed and toughened (specially tempered) in 
these cases, the analyst is constrained under the current standard to 
classify the article as ``tempered'' even though there may be doubts as 
to whether the article is actually tempered. Accordingly, the revised 
standard set forth in this document will afford the CBP analyst with 
the opportunity to utilize the center punch test in cases where the 
results of the cutting test are inconclusive (i.e., if the sample 
breaks into several large pieces when subjected to the cutting test).
    The second instance where the center punch test will be employed 
under the proposed revised method is cases where an article is too 
small to safely analyze with the cutting test. CBP believes this is 
necessary because the integrity of a tempered glassware article can 
fail during a cutting test, potentially resulting in serious injury to 
the CBP analyst. Accordingly, the revised method will afford the 
analyst the opportunity to utilize the center punch test on articles 
considered ``too small'' to safely perform a cutting test. The revised 
method will make clear that glassware articles considered too small to 
analyze safely with a cutting test will be those that are smaller than 
five inches in diameter or five inches wide. If a glassware article is 
smaller than five inches in diameter or five inches wide and the 
analyst chooses to use the center punch test, a cutting test will not 
be performed on the article and the results obtained from the center 
punch test will be considered independently. Results obtained from the 
center punch test in these situations will be interpreted in the same 
manner as results obtained from the cutting test.

Comment:

    The commenter states that the proposed breakage analysis for 
tempered glassware subjected to the cutting or center punch test 
(particularly fluorosilicate which has characteristics unique to its 
crystalline structure) is too subjective and in many instances would 
result in an erroneous conclusion that a tempered article is not 
tempered. With respect to the proposed breakage analysis, the commenter 
specifically states that both annealed and tempered fluorosilicate 
plates which are subjected to the center punch test break into small 
pizza-shaped pieces, the only real difference being that the tempered 
plates take more force to break and yield somewhat smaller pizza-shaped 
pieces. In addition, other types of articles may react differently when 
subjected to the center punch test. For example, a tempered mug which 
is subjected to the center punch test may break into irregular pieces 
smaller than those of an annealed mug.
    The commenter indicates that their client has performed repeated 
center punch tests on the full range of fluorosilicate articles which 
they manufacture and have confirmed that other than the differences in 
the appearance of the pieces noted above, they did not observe dicing 
or crazing of tempered fluorosilicate glass. The commenter submitted 
various photographs and ten short videos in order to demonstrate the 
difficulty associated with classifying glass as tempered or non-
tempered based on breakage patterns. The commenter states that the 
photographs depict annealed and tempered fluorosilicate (opal) and soda 
lime plates subjected to the center punch test. The commenter indicates 
that of the ten videos submitted, two are of the center punch test 
performed on tempered fluorosilicate glass plates; two are of the 
center punch test performed on annealed fluorosilicate glass plates; 
one is of the center punch test performed on a tempered soda lime glass 
plate; one is of the center punch test performed on an annealed soda 
lime glass plate; one is of a hammer striking a tempered fluorosilicate 
plate; one is of a hammer striking an annealed fluorosilicate plate; 
one is of the center punch test performed on a tempered fluorosilicate 
mug; and one is of the center punch test performed on an annealed 
fluorosilicate mug.
    The commenter believes that the photographs and videos prove that 
the breakage differences resulting when the

[[Page 55814]]

center punch test is performed on tempered versus annealed glass can be 
so subtle as to be virtually non-existent. The commenter specifically 
notes that tempered fluorosilicate glass plates will not exhibit any 
dicing, graveling, or crazing when cut or center punched. In addition, 
the commenter states that dicing, crazing, or graveling are 
characteristics that are generally exhibited in heat-treated flat 
glass, not flat glassware. The commenter contends that because tempered 
dinnerware is very different in shape and thickness, dicing, crazing or 
graveling does not ordinarily occur in soda lime glass dinnerware and 
never occurs in tempered fluorosilicate glass dinnerware. Moreover, the 
commenter states that there is no evidence that glass dinnerware should 
dice, craze, or gravel when cut.

CBP's Response:

    CBP disagrees with the commenter's statement that the analysis of 
breakage patterns for tempered glassware subjected to the cutting or 
center punch tests is too subjective to be deemed reliable. In 
addition, CBP notes that some degree of temper must be visually evident 
for a glassware article to be considered ``toughened (specially 
tempered)'' and also maintains that a tempered glassware article will 
craze, dice, or gravel when broken.
    CBP notes that the degree of temper in glassware is roughly 
equivalent to the strength increase of the glass produced by the 
compression on the outside of the article and that this increase in 
compression is compensated for by a greater amount of internal tension. 
CBP's view is that, at some point, the appearance of dicing indicates a 
certain amount of achievement of strength through tempering and that 
progressively smaller fragments corresponds to even higher levels of 
temper. The factor affecting whether an interior crack branches into 
other fractures is principally the state of the stress at those 
interior points through which the crack propagates. CBP's criterion for 
``toughened (specially tempered)'' translates roughly into the 
requirement that the state of tensile strength in the interior of the 
article due to tempering should be high enough to produce this 
branching which is exhibited by visible dicing, crazing, or graveling 
during breakage through at least part of the article. In this respect, 
whether it is flat glass or dinner glassware, it is a common axiom that 
a tempered glassware article will craze, dice, or gravel when it 
breaks.
    With respect to the photographic and video evidence submitted by 
the commenter, CBP initially agrees that in some cases the tempered 
glassware depicted in the submissions does not appear to craze, dice, 
or gravel when impacted with a center punch. However, it is noted that 
no evidence was submitted to demonstrate that the glassware subjected 
to testing in the submissions was, in fact, tempered. In addition, CBP 
notes that the experiments were not technically accurate because only a 
hammer was used in some of the tests. Accordingly, the criteria for 
interpreting breakage for the cutting test for opaque glassware and the 
reinstated center punch test, as set forth in the January 9, 2008, 
notice, will not be eliminated from the revised method for the testing 
of pressed and toughened (specially tempered) glassware.

Comment:

    The commenter states that CBP's proposal to use additional tests to 
verify the results of the other tests is improper because tests that 
are never disclosed or described cannot be properly scrutinized. In 
addition, the commenter states that CBP has not explained what weight 
would be assigned to the additional tests for purposes of applying the 
testing methodology.

CBP's Response:

    CBP agrees that the verification of additional test results would 
be problematic for the reasons the commenter provides. Accordingly, 
additional tests will not be used to verify the results of the other 
tests, as reflected in the revised method to be applied for the testing 
of pressed and toughened (specially tempered) glassware which is set 
forth below.

Conclusion

    After analyzing the comments and other material contained in the 
submission discussed above and further review of the matter, CBP has 
decided to adopt, except for the use of additional tests as discussed 
in the comment section above, the modifications to the test method used 
by CBP for the testing of pressed and toughened (specially tempered) 
glassware as proposed in the notice of January 9, 2008 (73 FR 1640) for 
the cutting test for opaque glassware and for the reinstatement of the 
center punch test for articles less than five inches in diameter and 
for inconclusive results from the cutting test. In addition, this 
document inserts a new section, ``Scope and Field of Application'', 
into the test method. This new section merely clarifies that the method 
employs macroscopic analysis, thermal shock testing, and evaluation of 
temper. This new section also clarifies that pressed and toughened 
(specially tempered) glassware articles are normally imported under 
subheadings 7013.28.05, 7013.37.05, 7013.42.10, 7013.49.10, and 
7013.99.20, HTSUS, and that articles normally imported under heading 
7007, HTSUS, such as windshields, are not within the purview of the 
method. Finally, this document makes other minor editorial changes to 
the test method. The revised test method, set forth in its entirety 
below, will be employed by CBP on glassware entered, or withdrawn from 
warehouse, for consumption on or after 30 days from the date of 
publication of this document in the Federal Register.

TESTING METHOD OF PRESSED AND TOUGHENED (SPECIALLY TEMPERED) GLASSWARE

    SAFETY PRECAUTION: CERTAIN PROCEDURES DESCRIBED IN THIS METHOD POSE 
A POTENTIAL HAZARD TO PERSONNEL FROM THE PROXIMITY TO OR HANDLING OF 
BREAKING OR BROKEN GLASS. THIS METHOD SHALL NOT BE UNDERTAKEN WITHOUT 
SUPERVISORY CONCURRENCE THAT ADEQUATE PRECAUTIONS FOR PERSONAL SAFETY 
HAVE BEEN IMPLEMENTED.

SCOPE AND FIELD OF APPLICATION

    This method employs macroscopic analysis, thermal shock testing, 
and evaluation of temper to determine if a glassware item has been 
pressed and toughened (specially tempered) for U.S. Customs and Border 
Protection (CBP)'s tariff classification purposes.
    These glassware articles are normally imported under subheading 
numbers 7013.28.05, 7013.37.05, 7013.42.10, 7013.49.10, and 7013.99.20 
of the Harmonized Tariff Schedule of the United States (HTSUS). 
Articles of ``safety glass, consisting of toughened (tempered) * * * 
glass,'' normally imported under heading 7007 of the HTSUS, (e.g., 
vehicle windshields) are not within the purview of this method.

1. APPARATUS:

    Photographic Equipment:
    A camera (equipped with flash or supplemented by adequate lighting) 
is recommended for making a permanent record of unusual samples and 
test results.
    Polariscope:
    The basic instrument consists of a light source, a polarizer, and 
an analyzer. The addition of a full-wave retardation, or tint, plate 
permits observation of color-enhanced stress patterns. Ideally, the 
working space, or

[[Page 55815]]

distance between the polarizer and the analyzer, should be large enough 
to accommodate samples ranging up to eight inches in height.
    Tile Saw (or Similar Table-Mounted Circular Saw):
    A tile saw having a cutting head which can be adjusted horizontally 
and vertically and which is equipped with an 8 to 12 inch diameter 
continuous rim diamond blade designed for wet cutting glass is adequate 
for testing opaque glassware articles.
    Center Punch:
    The center punch is a slender tool having one end tapered to a 
point. The tool should be approximately 8''; to 12'' in length to 
permit insertion into tall-form tumblers and other articles of similar 
shape while the nonpointed end extends above the rim. This is necessary 
for ease of handling and for safety while performing the center punch 
test. The pointed end of the center punch should not be sufficiently 
sharp so as to chip the glassware on contact without the application of 
pressure.
    Other Apparatus and Supplies:
    The method requires various common laboratory articles such as a 
caliper or similar device for measuring the diameter of the opening and 
the maximum inside diameter of the sample, an oven, a water bath, and 
other equipment and supplies. Appropriate safety devices and personal 
protective equipment are also required.

2. PREPARATION OF THE SAMPLE

    When available a representative number of samples should be 
analyzed. However, it is recognized that for any of several reasons, 
e.g., cost of the item, only a limited number of samples may be 
submitted for analysis. The possibility exists that only one sample may 
be available for testing.

3. ANALYSIS PROCEDURES

    The following procedures may be conducted in whatever order the 
analyst deems is appropriate for the particular sample being examined. 
The test protocol should be terminated at the point that a sample fails 
to meet any of the key criteria, i.e., ``pressed'', ``toughened'', or 
``specially tempered.''

Evaluation for Determination if an Article Has Been Pressed

3.1 Macroscopic Analysis:

3.1.1 Visual Inspection:

    Inspect the sample for the following:
     Identifying marks, labels, sizes, etc., especially those 
that may have been caused by a push-up valve and a mold that have been 
pressed into the article;
     The style (stemware, tumbler, bowl, plate, etc.);
     The presence of ribs, handles, flutes, etc.;
     The size of the rim or opening, if applicable;
     The size of the most bulbous portion of the article;
     Any other unusual characteristics (e.g., chips, cracks).
    Interpretation of Visual Inspection Results: Characteristics such 
as mold marks, ribs, handles, and flutes are often indicative of a 
pressed rather than blown glass article.

3.1.2 Dimensional Measurement (Applies Only to Stemware, Tumblers, 
Bowls, etc.):

    Using a caliper or similar device, measure the minimum diameter of 
the mouth, opening, or upper rim of the sample. With the same device, 
measure the maximum inside diameter. Record both measurements.
    Interpretation of Dimensional Measurement Results: A sample having 
a maximum inside diameter greater than the minimum diameter of the 
mouth, opening, or upper rim is not likely to have been ``pressed.''
    Interpretation of the Macroscopic Analysis Test: The analyst is 
advised to consider the overall features of the article and the 
dimensional analysis test results in determining that an article has 
been ``pressed.'' If the results show that the sample is not 
``pressed'', the testing sequence for this sample should be terminated 
at this point.

Evaluation for Determination if an Article Has Been Toughened 
(Specially Tempered)

3.2 Thermal Shock Test:

     Heat the sample(s) in an oven to 160 [deg]C for 30 
minutes.
     Remove one sample from the oven and immediately immerse it 
in a water bath set at 25 [deg]C. This results in a 135 [deg]C 
difference in temperature. [Note: Reasonable alternate oven and water 
bath settings up to  10 [deg]C are acceptable as long as 
the 135 [deg]C difference in temperature is maintained.]
    Interpretation of Thermal Shock Test Results: Annealed glassware 
and inadequately or partially tempered glassware will generally not 
survive this test of durability or toughness. If breakage occurs, the 
sample is not ``toughened'' for CBP purposes. Record the findings, and 
terminate the analysis.

3.3 Evaluation of Temper:

3.3.1 The Polariscopic Examination (For Transparent or Translucent 
Articles):

    This method for the qualitative evaluation of temper in glassware 
should be conducted only on transparent or translucent articles. This 
method is not applicable to opaque items or to articles which have been 
tempered by a process other than thermal tempering. In addition, some 
translucent articles will not transmit enough polarized light to permit 
the observation of stress patterns; these items should be evaluated for 
temper using the Cutting Test.
     Place the full-wave retardation plate (tint plate) between 
the polarizer and the analyzer. The polarized light must pass through 
both the sample and the retardation plate for the color-enhanced 
polariscopic pattern to be observed through the analyzer. Position the 
retardation plate in direct contact with the polarizer or, 
alternatively, just in front of the analyzer.
     Turn on the light source.
     Evaluate the stress in the bottom of the intact article by 
placing its bottom surface in contact with the polarizer so that the 
polarized light passes perpendicularly through the bottom surface, or 
as close to perpendicularly as possible, depending upon the article's 
shape. [This positioning does not work well with stemware because of 
color patterns caused by the stem itself. With these items, it will be 
necessary to hold the glass at a slight angle to view the base and the 
bowl separately.]
     Evaluate the stress in the sides of the intact article, 
especially near the rim or edge, by positioning the article so that the 
polarized light passes perpendicularly through the sides near the rim, 
or as close to perpendicularly as possible, depending upon the 
article's shape. Observation of the stress patterns in the sidewall and 
rim areas should be made while viewing through a single thickness of 
glass. For some items, especially stemware, tumblers, and mugs, this 
will require holding the article at a slight angle to the polarizer 
(open end raised slightly).
    Interpretation of the Polariscopic Examination: Thermal tempering 
of glassware involves heating to the softening point followed by rapid 
cooling. The surfaces cool first and reach a temperature where they 
become rigid. With further cooling, the interior or core tries to 
shrink but is prevented from doing so by the rigid surface layers. This 
results in the surfaces being locked into a state of high compression 
and the interior locked into compensating tension.
    When polarized light travels through a stressed material, they 
divide into slow and fast fronts. As a result of the difference in 
speed of the slow and fast rays, interferences occur and a pattern of 
colors is observed. These colors can

[[Page 55816]]

be used to evaluate the stresses in the article. As the stress 
increases, the observed color changes to reflect the amount of stress. 
The color changes follow a rigorous sequence as the stress-induced 
retardation, or distance between the fast and slow rays, increases. In 
low-stress areas, black and shades of gray are seen. Evaluation of low 
stress is simplified by using a color-enhancing retardation or tint 
plate which adds a shift of one fringe order, or 565 nm, in the color 
pattern throughout the observed field. With the tint plate in place, 
even low and moderately stressed areas will exhibit a contrasting color 
effect.
    Annealed glassware will exhibit a uniform coloration of the 
polarized light passing through it; there will be essentially no change 
from the background. Tempered articles will exhibit non-uniform 
coloration of the polarized light on the bottom surface and sidewalls 
and bands of color parallel to the rim or lip. [Note: With highly 
colored articles, it may be helpful to conduct the polariscopic exam 
without the tint plate. There will be no color enhancement, but the 
gray to black interference patterns should be readily discernible in 
tempered articles.]
    If the sample passes the Thermal Shock Test and shows evidence of 
full-surface tempering (as opposed to rim-tempering or partial 
tempering) when examined polariscopically, the sample has been 
``toughened (specially tempered)'' for CBP purposes.

3.3.2 The Cutting Test for Opaque Glassware

    This test is applicable to opaque articles and to those translucent 
articles which cannot be examined polariscopically because of 
inadequate transmission of the polarized light.
     Ensure that the saw is equipped with a continuous rim 
diamond blade designed for wet cutting glass.
     Adjust the cutting head of the saw vertically and 
horizontally, as necessary, to accommodate the glassware article.
     Be sure the water supply to both sides of the diamond-
rimmed blade is adequate.
     Turn on the saw.
     While holding or otherwise securing the article to prevent 
twisting and binding during the cutting, slowly and gently move the 
article into contact with the blade.
     Proceed with the cutting.
     Note the breakage pattern, number, and relative shape and 
size of the fragments (indicate this without making an actual count). 
Photograph the breakage pattern and/or typical fragments, if indicated.
    Interpretation of the Cutting Test: Annealed (non-tempered) 
glassware will readily accept the diamond-rimmed blade and will be 
cleanly cut in half. Tempered glass, on the other hand, will break into 
pieces when cut. The broken pieces will need to exhibit some dicing, 
crazing (gravel remaining tenuously in contact with neighboring pieces) 
or graveling. ``Some'' will be considered to be any diced, crazed or 
graveled fragments yielded by the broken sample that is more than just 
a fugitive diced, crazed or graveled fragment. The word ``gravel'' is 
intended to be synonymous with ``diced pieces'' and implies the 
presence of small cubes of roughly equal dimensions on all six sides. 
The extent of cutting needed to induce breakage may vary from item to 
item, but in no event will tempered articles be cleanly cut in half by 
the diamond-rimmed blade.

3.3.3 Center Punch Test

    In the event that the Cutting Test is inconclusive (i.e., if the 
sample breaks into several large pieces when subjected to the cutting 
test) or if an article is too small (less than 5'' in diameter) to be 
safely analyzed by the Cutting Test, the analyst has the option to 
apply the Center Punch Test to the article. The Center Punch Test 
should be performed as follows:
     Set the sample to be tested on a solid, level surface.
     Place an upended cardboard box over the item to be tested. 
The box should be of sufficient size so that the entire article is 
covered. The box should be altered such that there is a hole in the 
center which is large enough to admit the shank of a center punch.
     Place the pointed end of the center punch, vertically, 
against the inside center bottom or heel.
     Strike the dull end of the punch with a hammer, using 
blows of gradually increasing severity, until breakage occurs.
     Note the breakage pattern, number, and relative shape and 
size of fragments (indicate this without making an actual count). 
Photograph the breakage pattern and/or typical fragments, if indicated.
    Interpretation of Center Punch Test Results: In order to be 
considered ``tempered'' for CBP purposes, it is only necessary for the 
broken sample to exhibit some dicing, crazing or graveling. ``Some'' 
will be considered to be any diced, crazed or graveled fragments 
yielded by the broken sample that are more than just fugitive diced, 
crazed or graveled fragments. The word ``gravel'' is intended to be 
synonymous with ``diced pieces'' and implies the presence of small 
cubes of roughly equal dimensions on all six sides.
    ``Toughened (specially tempered)'' glassware will require 
considerably more force to break than ordinary glassware with the 
center punch test and, when it breaks, some graveling or crazing will 
be observed. Neither graveling nor crazing will be observed in ordinary 
glassware.
    Powder and splinters will occasionally be observed in samples of 
``toughened (specially tempered)'' glassware. Also, few, if any, of 
these samples will be reduced entirely to gravel; larger fragments will 
remain. However, these large fragments will seldom be exceptionally 
pointed or jagged and broken edges, especially on diced pieces, will be 
reasonably dull.
    The stem and base of the stemware styles seldom disintegrate. The 
most common breakage pattern for stemware is characterized by a tack-
shaped fragment consisting of the base and a portion of the stem 
remaining intact. The tip of the stem portion should be reasonably 
dull.
    A sample that passes the Thermal Shock Test and shows evidence of 
tempering per the guidance given above for the Cutting Test and/or 
Center Punch Test has been ``toughened (specially tempered)'' for CBP's 
tariff classification purposes.

    Dated: September 9, 2010.
Ira S. Reese,
Executive Director, Laboratories and Scientific Services, U.S. Customs 
and Border Protection.
[FR Doc. 2010-22826 Filed 9-13-10; 8:45 am]
BILLING CODE 9111-14-P