Understanding glass test report

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Understanding OTM glass optical & thermal property test report

Test reports are issued by OTM for glass optical & thermal property testing services. This article aims to provide a detailed explanation on the content of our test report.

A typical OTM glass test report (sample report) consists of the following sections:

Frequently asked questions (FAQs) on OTM glass test reports:

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Sample test report

A sample glass optical & thermal property test report is available here.

The discussions below are based on this sample report.

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Cover page

The cover page lists important information, including client information, laboratory information, report number, job description, approval signature, and test/report dates.

The client information part lists client’s name and address and the information needs to be declared by client in writing.

More information
  • Client: client’s name and address. This information needs to be declared by client in writing.
  • Laboratory: laboratory name, company name, address, and contact information. For test within our SAC-SINGLAS accreditation scope, the accreditation information is also listed here.
  • Report number: each report is assigned a unique report number, in the format of OTMYYMMNNN (YY: 2-digit year; MM: 2-digit month; NNN: 3-digit running number; example: the first report issued in January of 2022 is assigned the report number OTM2201001).
  • Job description: a simple description of the test and sample; the dates that the sample is received, and the test is conducted.
  • Approval signature: we issue manually signed hardcopy reports only. The signed hardcopy reports are scanned to softcopy reports in the PDF format for electronic transmission. We do not issue unsigned or electronically signed softcopy reports.
  • Date of test: the date that the test is conducted.
  • Date of report: the date that the report is finalized.

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Test method description

The test method description section lists essential technical information related to the test, including test methods, instruments, environmental conditions, calculation software, estimated uncertainties, and notes.

More information
  • Methods: the relevant NFRC, EN or ISO test method used in the test (refer to this article for a comparison between the test methods)
  • Instruments: the instruments used in the test
  • Environmental conditions: the laboratory space temperature and humidity during the testing.
  • Calculation software: the software tools used in test result calculations.
  • Estimated uncertainties: the estimated uncertainties of the test results (refer to this article for some information on our measurement accuracy).
  • Notes: further explanatory notes to the test report. Examples: 1) how to convert the results from decimals to percentages; 2) calculation method of non-standard results; 3) special practices specific to the current test.

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There are 4 standard disclaimer clauses in our test reports. Expand the “More information” block below for more details.

More information
  • The test report shall not be reproduced except in full, without written approval of the laboratory.
    When sharing the test report to other relevant parties, the full content of the report shall be shared.
  • The sampling was not performed by the laboratory. The test results relate only to the sample received and tested.
    The sampling is performed by the client. The responsibility of proper sampling is with the client. The laboratory does not perform sampling.
  • The sample description information was declared by the client and it may affect the validity of the results.
    The sample description is declared by the client. The responsibility of accurate sample description information is with the client.
    The laboratory can only do basic verifications of the declared sample description (e.g. color and thickness), but cannot do full verifications.
  • The test report is issued subject to the “Testing Service Terms and Conditions” annexed to OTM official quotation and on request from OTM.
    More terms and conditions of the testing services are defined in the “Testing Service Terms and Conditions”.

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Glazing system description

The glazing system description section lists sample description and schematic.

More information

The sample description information of a glass needs to be declared by client in writing.

In the schematic, the layer-by-layer glass configuration is illustrated, such as glass, PVB interlayer, low-e coating, and air space.

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Glazing system test results

Shown below is a typical standard result table based on the NFRC method (sample report):

A detailed explanation of the results is available in this article.

The spectral transmittance/reflectance curves are also presented graphically.

More information

There are some variations depending on the test method and sample type, as listed in the table below:

EN or ISO test methodThe names of some quantities are different (refer to this article for details)
The NFRC summer condition U-value is reported as the summer condition U-value
The original EN or ISO U-value is reported as the winter condition U-value
Double glazing unit (DGU)In addition to the glazing system test results, the test results of each glass pane are also reported (refer to this article for details)
Glass with window filmBy default, three additional results are reported: UV transmittance, UV rejection and light-to-solar-gain (LSG) ratio
On request, other additional results relevant to window film products can be reported.
Partially fritted glassIn addition to the glazing system test results, the test results of the clear part and the fritted part are also reported (refer to this article for details)
Further extended resultsOn request, more extended results can be reported (refer to this article for details)

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Sample photos

The sample photos section lists photos of test samples, including zoom-in views of labels.

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Frequently asked questions (FAQs) on OTM glass test reports

If your concerned questions are not answered, please feel free to leave a comment at the end of this page. This article will be reviewed and updated regularly.

Do you provide hardcopy or softcopy reports?

We provide both hardcopy and softcopy reports.

Each hardcopy copy is manually signed and only 1 copy is issued to the client. The signed hardcopy is also scanned to the PDF softcopy format.

By default, hardcopy reports are couriered to the client and softcopy reports are emailed.

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Can your client review a test report before it is issued?

By default, we email a draft report in PDF format with the “DRAFT” watermark for client’s review. The client has 1 working day to revert to us should some amendments are applicable.

However, we are an independent third-party test laboratory, and we wish to clarify the following:

  • The draft report is for the client to review the client declared information only (i.e. client’s name/address and sample description) and to access the test results earlier.
  • On the other hand, the draft report is not for client’s approval nor acceptance. In principle, we do not accept report amendment requests other than the client declared information mentioned above, unless there are valid technical reasons.

Please refer to the FAQ “can a test report be amended?” below for more details.

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Can a test report be amended?

In principle, the following client declared information in a test report can be amended with a request in writing:

  • Client’s name and address
  • Sample description

We do not accept other report amendment requests (such as report format and test results) unless there are valid technical reasons.

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Can multiple test reports be issued for one test?

Yes, it is possible to issue multiple test reports for one test.

In the multiple test reports, the client’s name and address information and the sample description information could be different, with the same principle mentioned in the FAQ above.

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Do you verify client declared information?

A client needs to declare the following information:

  • Client’s name and address
  • Sample description

The responsibility of declaring accurate information is with the client. This is required in our “Testing Service Terms and Conditions” and is also part of the disclaimer in a test report.

It is out of our scope to do full verifications of the information declared by the client. We will still do some verifications within our capabilities. The verifications include, but are not limited to, the following:

  • Sample thickness
  • Sample appearence (typically color)
  • Coating, window film or interlayer locations

If we notice that the client declared information is obviously inaccurate, we will not accept the information declared.

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Do you provide statement of conformity, or opinions and interpretations?

By default, we only report the test results objectively, without statement of conformity, or opinions and interpretations.

On request, we can provide statement of conformity in a test report, provided that the decision rules can be provided by the client (e.g. project specifications or contracts).

We do not provide opinions and interpretations in test reports strictly.

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Can you provide the raw data of a test?

Yes. On request, we can provide the raw data of a test in the IGDB data format.

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