Public Health - VOSI
Research Report RR7-V50.1
Updated: 12-08-2000
"UNIVERSAL
SPECIFICATION/TEST METHOD FOR CLASSIFYING AND MINIMIZING THE LEAD
CONTENT OF METAL CORE CANDLE WICKS & TO BAN METAL CORE
IMPORTED CANDLES"
REFERENCES
-
Model 90 Candle Wick Core Classification Test
Kit; Technical Products Co., N. Caldwell, NJ 07006
-
Material Safety Data Sheet (MSDS) for (Wire)
Zinc Base Alloys; Wire Industries, Inc., Dumar, AR
-
MSDS for Tin/Copper, Antimony/Silver Alloy;
Federated-Fry Metals, Altoona, Pa
-
Technical Report 17700, 8/2/2000; Intertek
Testing Services, Totowa, NJ
-
Technical Report 17810, 9/12/2000; Intertek
Testing Services, Totowa, NJ
-
ASTM E1613-99 "Standard Test Method for
Determination of Lead by Inductively Coupled Plasma Atomic
Emission Spectrometry (ICP-AES), Flame Atomic Absorption
Spectrometry (FAAS), or Graphite Furnace Atomic Absorption
Spectrometry (GFAAS) Techniques
-
ASTM Proposed 9/00 "Standard for
Lead (Pb) Content in Wicks Used in the Production of
Candles"
-
Adams & Pearce 11/99 Pricelist for cotton,
paper & zinc core wicks
SCOPE
To classify the metal core of candlewicks based on
the tensile strength of zinc, tin and lead cores and to measure
the lead content of it.
To determine if the tensile strength of zinc
alloys correlates with the lead content when tested per ref. 6.
To determining the burning rate of tealight
candles with zinc, tin, lead, paper and cotton core wicks.
CLASSIFICATION & % LEAD
The following tin and zinc core candlewicks were
received from Jeb Head, chairman of the ASTM Candlewick Task
Group, of Atkins & Pearce, Inc., Covington, KY:
|
tin core wicks |
zinc core wicks |
|
(1T) …51-31=18T |
(1Z)…51=36=18Z |
|
(2T)….36-24-24T |
(2Z)… 36-24=24Z |
|
(3T)…10-38T |
(3Z)… 32-10=38Z |
Using the Technical Products Model 90 Wick
Classification Test Kit (ref. 1), tensile tests were performed on
the aforementioned six tin and zinc core wicks. In addition the
writer had a box of lead core candles with no identification
except the word "citronella";
one of the lead core candles was tested.
The ref. 4 test report for % lead is summarized in
Table 1 for the tin, zinc and lead core wicks. An unwaxed cotton
wick contained 0.003% Pb. A waxed cotton wick contained 0.006% Pb.
A red imported candle was supplied by Jim Becker (American
Greetings, Inc.) chairman of ASTM F 15 "Consumer
Products" subcommittee F15.45 on "Candle Products"
and ASTM Task Group on Candle Wicks member, supplied both the red
imported candle and tealights for VOSI testing. The red imported
candle, without a metal core, contained 0.008% Pb and the imported
tealight candle wick, without metal core, contained 0.003% Pb.
These values prove that the maximum % lead should be set at 0.010%
(100 ppm)
Table 1 summarizes the tensile tests and lead
content of the tin, zinc and lead wicks.
F1 is the uncorrected breaking force, and
F2 is the corrected force after calibrating the force gage.
D is the core wire diameter, inches, before testing and is the
diameter used for calculating S, the tensile stress, in psi.
The % lead was measured in accordance with ref. 6
by Intertek (ref. 4) using the Inductively Coupled Argon Plasma
test method which is accurate to 10 ppm (.001%).
Table 1.
|
Tensile Strength & Lead Content of
Metal Cores |
| |
Tin |
Zinc |
Lead |
|
1T |
2T |
3T |
1Z |
2Z |
3Z |
1L |
|
Dia. |
0.0185 |
0.0187 |
0.0117 |
0.0139 |
0.0143 |
0.0143 |
0.0183 |
|
F1-lb |
1.78 |
1.75 |
0.51 |
3.78 |
3.95 |
4.07 |
0.52 |
|
F2-lb. |
1.5 0 |
1.45 |
0.35 |
3.6 0 |
3.72 |
3.8 0 |
0.32 |
|
S – psi |
5566 |
5283 |
3247 |
23663 |
23176 |
23675 |
1106 |
|
S- Average |
|
4700 |
|
|
23505 |
|
1106 |
|
Lead - % |
0.04 |
0.04 |
0.026 |
0.006 |
0.006 |
0.01 |
18.3 |
|
Lead Average |
|
0.023 |
|
|
0.007 |
|
18.3 |
A metal core candle wick, Walnut Hill Co.,
Bristol, Pa, 10 ft. long and designated W-1 wire, B-1 braid for
candles less than 2" diameter, was purchased by the writer at
a craft shop. The tensile strength of this material at 0, 5 and 10
ft. were 15,312, 18,119 and 18, 178 respectively.
The lead content, tested per ref. 5 at 0, 5 and 10
ft, was 0.016, 0.014 and 0.015 respectively. Since the Table 1
minimum tensile strength was 23,176 for this "special high
grade zinc alloy" and the maximum % lead was 0.010% the %
lead appears to vary inversely with the strength, and quality of
the zinc alloy. The 0.01 % lead is greater than the 0.006% maximum
lead specified on the MSDS (Ref 2.).Further testing is required to determine whether
tensile testing can be used to classify the % lead of zinc alloy
metal cores in addition to determining whether the core is tin or
lead. This could eliminate the need to use the ref. 6
sophisticated test method for insuring that zinc alloys contain
less than 0.010% lead.
Based on the above, the breaking force (F2), based
on a minimum 20,000 psi tensile strength for a high grade zinc
alloy with .01% maximum lead content is listed in Table 2. and
ref. L, based on wire diameters from 0.010 to 0.020 inches.
Table 2.
|
Breaking Force (F2) vs. Zinc Core Diameter |
| |
0.010 |
0.011 |
0.012 |
0.013 |
0.014 |
0.015 |
0.016 |
0.017 |
0.018 |
0.019 |
0.020 |
|
F2-lbs |
1.6 |
1.9 |
2.3 |
2.7 |
3.1 |
3.5 |
4.0 |
4.5 |
5.1 |
5.7 |
6.3 |
BURNING RATE
Tealight candles, from American Greetings (black
cherry), having a l 7/16" diameter and 5/8" height and
.090 center hole diameter, were used for evaluating the burning
rate of the candles using tin and zinc metal core wicks and paper
and cotton core wicks supplied by Atkins & Pearce, Inc. The
wicks were wax coated by dipping in the same melted wax as the
tealight candles used. In addition the previously mentioned lead
core citronella votive candle was tested.
Table 3. lists the wick diameter (D), weight of
the candle wax both before and after testing in a ventilated hood,
and the burning rate in minutes/gm of candle wax.
Table 3.
|
Burning Rate |
| |
Tin |
Zinc |
Paper |
Cotton |
Lead |
|
Wick Dia. – in. |
0.065 |
0.057 |
0.078 |
0.065 |
0.070 |
|
Initial Wgt. - gm |
15.2 |
15.2 |
15.2 |
15.4 |
52 |
|
Final Wgt. - gm |
0.7 |
0.7 |
0.4 |
14.5 |
10 |
|
Burn Time – min. |
178 |
215 |
158 |
---- |
542 |
|
Minutes/gm |
12.3 |
14.8 |
10.7 |
---- |
12.9 |
|
Ranking (slow) |
3 |
1 |
4 |
|
2 |
Table 3. indicates that zinc core candles have the
slowest burning rate and paper the fastest. Lead was supposedly
used because of its slow burning rate however zinc is superior to
lead. The cotton core candlewick quickly extinguished itself.
Based on the highest burning rate, the paper core wick would be
the most profitable to use and would eliminate the need to use any
metal core wick.
CONCLUSIONS
-
The .01% maximum lead content can be met in
high-grade (high tensile strength) zinc alloy cores.
-
Paper core wicks can be used to replace all
metal cores by sacrificing long burn time.
-
Tensile strength can be used to classify metal
core wicks in order to ban the use of tin and lead cores.
-
Tensile testing is the only practical way for
custom inspectors to test imports for lead or zinc content. A visual inspection can be used to ban imported metal core wicks and candles.
-
Further testing is required to verify that
tensile testing of zinc alloys can be used to measure the .01%
maximum lead content and eliminate the use of a sophisticated
laboratory test method (ref. 6).
-
Western Europe has banned metal core candle
wicks. The United States, as a World Health
Organization (WHO) member, should use public health standards
which are equal to or better than those of any WHO member
nation.
ADDENDUM : 12-08-2000
TENSILE STRENGTH & % LEAD IN WIRE INDUSTRY'S
308 ZINC ALLOY
WIRE
A 10 foot long sample of 0.014" diameter was cut
in half. Six wires, 2" long were cut from one end and three pieces
were cut from the other end of each 5' length. Each piece was
identified as 1, 1A, 1B, ....6, 6A, 6B and placed in separate envelopes before testing.
Test Lab: Intertek Testing Lab, Springfield, N.J.
Date Tested: 11/30/00
Test Method: Inductively Coupled Argon Plasma (ICP)
Test Instrument: Atomscan "Advantage" ICP
Test Lab: SGS/U.S. Testing, Fairfield, N.J.
Date Tested: 11/30/00
Test Method: Atomic Absorption Spectroscopy (AAS) (nitric acid
digestion)
Test Instrument: Varian Flame AAS, Model AA-20
RR7-50.1, ref. 2, Material Safety Data Sheet (MSDS)
specifies: "Lead Range 0 - .006%"
The average % of Lab B, using AAS, is 0.002% whereas
the Lab B ICP method was 0.008%.
Donald C. Meserlian, P.E.
VOSI Chairman
