TFT 3 User manual

TFT TYPE 3 DIGITAL REFLECTOMETER
Overview
The TFT Digital Reflectometer is used to measure the whiteness of fabrics or materials. It measures the
percentage of light in the visible part of the spectrum reflected from the test surface. The readings are typically
used to identify trends in laundry effectiveness and to provide a quantitative measure that can be used as
acceptance criteria.
The reading does not include any contribution from ultraviolet or infra-red light.
TFT also make and supply a meter to measure the amount of ptical Brightening Agent ( BA) in a sample. The
BA meter uses an ultraviolet light source which causes the material containing the BA in the material to
fluoresce, giving off light in the blue part of the visible light spectrum. This visible light is measured by the meter
to give a reading of the amount of BA in the material.
Contents
The Reflectometer is supplied in a padded plastic carry case which provides physical protection for the contents.
The carry case contains:
•Type 3 Digital Reflectometer
•Calibrated ceramic reference tile
•Mains-powered battery charger (which may also be used for a TFT BA meter)
The calibration certificate is supplied separately in hard copy and/or as a pdf document.
Before first use
The meter screen is covered with a protective plastic film which can be peeled off.
The meter is supplied part-charged and is ready for use as received. If the red light is lit, the meter needs to be
charged – see below for instructions.
Sam le re aration
The Reflectometer measures the amount of light reflected from the surface presented to the glass slide on the
base. Samples should be prepared that are large enough to cover the whole glass area at least.
Care needs to be taken to avoid the desk surface beneath the sample affecting the meter reading. A dark desk
surface could lead to a false low reading. Conversely, a light desk surface could lead to a false high reading.
To avoid this possibility, we recommend that material should be layered at least 4 layers thick. For more
transparent materials even more layers may be needed. The correct number of layers can be found
experimentally by adding layers and checking the reading each time until an extra layer does not significantly
change the meter reading.
The test sample should be as smooth and flat as possible in order to ensure consistency of the optical path
between the sample and the meter sensor. Any creases or folds in the sample will prevent the base of the
Reflectometer from sitting completely flat on the test sample creating shadow areas which will reduce the meter
reading.
TFT (Ilkley) Ltd.
The Sidings Business Park, SKIPTON, North Yorkshire, B 23 1TB
Email [email protected] or telephone [phone]
ffice address: 30 Alexandra Crescent, ILKLEY, West Yorkshire, LS29 9ER
ffice phone or fax: [phone]
Company Registration Number 3168606, VAT Number 659 9604 77

Using the meter
1. Place the Reflectometer on the calibrated reference tile supplied with it and move the slide switch to the
left. The green light indicates that the meter is switched on. The red light indicates a low battery (see the
section on charging for more information).
2. When switched on, the meter reading will drop from its initial value as the meter warms up. Allow one
minute warm-up time, or wait until the reading shows no further drop.
3. nce the reading is sufficiently stable, calibrate the meter by using the coarse and fine calibration dials on
the top face of the meter so that the display reads the value shown on the ceramic calibration tile and
certificate. ur calibration process ensures that your meter will then read 100% in the conditions outlined
in the certificate. This ensures that different Type 3 meters will give comparable readings.
4. Move the meter from the calibrated reference tile to the material sample to be tested, and record the
reading shown on the display. You must make sure that the sample covers the whole of the glass aperture
on the base of the machine. If the sample does not cover the whole area, the meter reading will include
some contribution from the desk surface giving a false reading.
5. After each reading return the meter to the calibrated tile. Before taking the next readings check that the
meter is still calibrated correctly and adjust if required.
6. Avoid using the meter very close to mobile phones or computers as the radiation they produce can cause
fluctuations in the meter reading.
Ensuring consistent readings
The TFT meter is sensitive to very small changes in light levels. As with all physical measurements, you will obtain
a more accurate reflectance value for each sample if several readings are taken and the results averaged. The
degree of variability will depend on the material under test. The material may not have the same whiteness across
the whole piece.
The orientation of the meter with respect to the material may affect the reading. This is more marked for materials
with rougher surfaces, such as terry towelling, twills or velvets, where the exact positioning of the pile strands will
create shadow areas which will affect the reading. In these cases, take particular care that the pile is flattened as
much as possible.
The number of readings you should take for each sample will be determined by the level of accuracy you require. If
you only need to know the whiteness within a range, a single reading may be sufficient. If you need a more closely
accurate reading we recommend you repeat the reading for each sample at lease 4 times, turning the sample by 90
degrees each time. By rotating the sample you will allow for the variation in whiteness caused by the fabric
structure. In most cases, this will give an acceptable degree of accuracy.
Even with a smooth cotton sheet this rotation can give a difference in reading of 3 or more units. If you need to
know the whiteness to a closer tolerance than this, the sample rotation and repeat readings are critical to getting
consistent, average results. You may also choose to measure both sides of a double-sided fabric.
The following table illustrates the sort of readings you may expect from following the above procedure:
North West South East Average
Material front 74 71.4 74.2 71.5 72.8
Material rear 73.6 71.5 73.3 71.5 72.5
These figures show that any single reading does not give a fair representation of the reflectance value for the
material overall.
If you need even higher accuracy, the number of repeats should be increased until you have the accuracy you
need. For the difficult fabrics mentioned above this could mean repeating the reading 8 or even 16 times.

Charging the batteries and battery care
1. When the red light on the top of the meter illuminates faintly there is approximately 3 hours of battery life
remaining before they are fully exhausted. The meter can be re-charged at this point. If you continue to
use the meter, the red light will eventually illuminate brightly and the meter must be switched off
immediately and recharged.
WARNING - Leaving the meter switched on beyond this oint may irreversibly damage the battery
acks. Take articular care to switch the meter off when testing is com lete.
2. To recharge the meter, plug the moulded DC plug on the charger into the socket on the end panel and plug
the charger into the mains socket. Switch on the mains supply. The charger will assess the state of the
battery charge and start a fast charge of the battery. A typical recharge time from flat is 3 hours using the
fast charger we supply. nce fully charged, the meter will operate for about 80 hours with new batteries
before it will need to be charged again. It is normal for the charger to get warm whilst charging.
3. A red light on the charger indicates that the unit is fast charging. nce the fast charge is complete, the
charger shows a green light. The unit is now charging on trickle charge.
4. nce the charger shows the green light it is best to disconnect the charger from the mains and from the
meter. Leaving the meter on charge for long periods is not recommended as it can reduce battery life, and,
if the batteries are old, may cause over-heating.
5. Do not leave the charger connected to the meter unless it is plugged in to the mains supply and the
electricity power is turned on. If the power supply to the battery charger is not turned on whilst connected
to the meter, the battery pack will discharge through the charger. This will completely exhaust the battery
packs and no amount of charging will make them hold charge again. New batteries will be required.
6. The meter cannot be used whilst the charger is plugged in.
7. As with all rechargeable batteries, the amount of charge they will hold will diminish with time. nce the
meter will not hold charge long enough for your pattern of use, the meter will need to be returned to TFT for
battery replacement. The battery life is checked each time the meter is returned for calibration and we will
offer the chance of battery replacement if they are found to be holding little charge.
Maintenance
1. The Reflectometer is supplied in a hard-wearing plastic carry case with moulded padding to reduce the risk
of damage whilst being carried.
2. When returning the unit to its carry case, always place the tile sideways (glazed face towards the base of
the Reflectometer) inside the case covering the base plate of the Reflectometer. This provides the best
protection for the tile and the glass slide against damage or scratching.
3. The meter is supplied sealed and contains N user-exchangeable or user-serviceable parts.
4. An annual service of the unit and calibration check of the ceramic reference tile is recommended - for
details of this facility please contact TFT on [e-mail], quoting your Reflectometer Serial Number
which is indicated on the end of the unit under the re-charge plug socket.

Contact Details
To contact TFT for sales, calibration or repair of meters please use the following contact details:
Email contact: [email protected]
Postal address: TFT (Ilkley)
Gate 4
The Sidings Business Park
Engine Shed Lane
SKIPT N
North Yorkshire
BD23 1TB
Telephone: [phone]
For payment or account queries, please use the details in the header of this document.
Guarantee
The unit is fully guaranteed against faulty workmanship or component malfunction for one year for both parts and
labour. In order to ensure that you are not inconvenienced by any breakdown we also undertake to correct any
fault within 48 hours of receipt of your unit. Carriage is payable for dispatch outside the European Community.
Caveat
The unit CANN T BE GUARANTEED against PHYSICAL MISUSE such as being dropped or immersed in water
etc. or if the RECHARGEABLE BATTERIES are VERDRAINED to the extent that they are in short circuit or
reverse polarity and CANN T BE RECHARGED, i.e. if the red LED is left illuminated for M RE THAN NE
H UR or the unit is put away without being switched FF.
Green = OnRed = Low battery
Indicator lights