Floating wick holder

A lamp comprising a wick-holder moulded in one piece from poly-4-methylpent-1-ene or like plastics material which is naturally buoyant upon combustible oil and which includes a central wick-retaining recess, a peripheral portion disposed above the recess, and at least one arm linking said recess to said peripheral portion and disposed below the peripheral portion. In use the lamp holder floats in oil with the central wick-retaining recess and the or each arm submerged and with only the peripheral portion floating.

BACKGROUND OF THE INVENTION 
This invention relates to a floating wick-holder which in use floats upon a 
body of combustible oil. 
It has hitherto been known to make floating wick-holders by injection 
moulding from a single sheet of plastics material and to provide 
air-containing buoyancy chambers to enable the holder to float. 
U.S. Pat. No. 3,183,688 (Sobelson) is an example of a wick-holder of the 
kind referred to above. It is a disc-like body formed from a single sheet 
of plastics material. It consists of a central wick support, a circular 
well portion defined by the inner surface of an annular rib, and an 
annular flotation portion defined between an outer wall of the wick-holder 
and the outer surface of the annular rib. The Sobelson wick-holder suffers 
from the disadvantages that in use the inner surface of the annular rib is 
in direct contact with the hot liquid in the well portion and that the 
upper bight portion of the annular rib is clear of the surface of the 
liquid and is exposed to the flame from the wick which is relatively close 
thereto. The annular flotation portion is open to the upperside and is 
liable to fill with liquid if the surface of the liquid is disturbed 
mechanically or by air currents with the result that the member can easily 
be made to sink. Furthermore, Sobelson is restricted to wick-holders of 
circular shape whereas consumers often desire more decorative shapes. 
German DAS 1 077163 (Glafey) shows a flower-shaped wick-holder in which a 
plurality of petal members are fixed around a circular stamen portion 
containing a wick support. Each petal has an internal flotation cavity 
open to the underside thereof. In use the Glafey wick-holder floats with 
the stamen portion submerged. Although the idea of providing buoyancy by 
means of air trapped in flotation cavities beneath the wick-holder reduces 
the risk of the wick-holder sinking, there is still a risk of it doing so, 
and more importantly the requirement for flotation cavities imposes a 
practical lower limit on the size of the petals. Thus the Glafey 
wick-holder cannot be used to reproduce flower shapes or complex abstract 
shapes consisting wholly of fine filaments because flotation cavities have 
to be provided. 
Another construction of wick-holder described in British patent 
specification No. 1,380,358 issued to RIZLA LIMITED consists of an 
imperforate, circular, one-piece, thin-walled member of a plastics 
material such as cellulose acetate, P.V.C. polystyrene or polypropylene, 
the member having a wall thickness of between 0.01 and 0.02 and preferably 
0.015 inches. It is illustrated in FIGS. 5 and 6 which are plan and 
cross-sectional views of an embodiment of the wick-holder described in the 
said British patent. 
In the device shown in FIGS. 5 and 6, the member 10 is moulded or 
vacuum-formed so as to have four portions 30 which define segmental 
flotation cavities opening to the underside of the member and separated by 
a flat area 20 which is cruciform in plan and which is below the level of 
the rims of the portions 30. When the member is set upon the surface 50 of 
a body of combustible oil, on which the member is caused to float because 
of the buoyancy-imparting effect of air trapped in the cavities 30, oil 
flows over the flat area to feed a wick W. The wick is supported in a 
recess within a tube 40 which projects down from the underside of the flat 
area and is located at the centre of the member. In use, the body of oil 
is supported on a non-flammable liquid such as water so that when the oil 
is exhausted the water floods over the flat area and extinguishes the 
wick. Because buoyancy is imparted to the member by trapped air there is 
again a reduced but not negligible chance of the member capsizing. More 
importantly the fact that the wick-holder is formed from a single circular 
sheet and the requirement for buoyancy chambers precludes the use of 
complex and artistically desirable shapes. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide wick-holders of plastics 
materials which can be made in a wide range of complex shapes and which do 
not require the provision of flotation chambers. 
It is also an object of this invention to provide wick-holders which can be 
formed entirely from thin rigid strips or filaments of plastics material. 
A further object of this invention is to provide a floating wick-holder 
which although formed from a plastics material is not liable to ignite or 
distort when the wick is alight or sink in the body of combustible oil if 
the surface of the latter is accidentally disturbed, and is suitable for 
manufacture by injection moulding. 
Accordingly, the invention provides a wick-holder which is moulded in one 
piece from poly-4-methylpent-1-ene or similar plastics material which is 
naturally buoyant in a combustible oil, such as vegetable oil, the 
wick-holder having a central wick-retaining recess which in use is 
disposed beneath the surface of a body of combustible oil when the 
wick-holder is set down thereupon. Poly-4-methylpent-1-ene is the full 
chemical name of the material commonly referred to in the art as 
"polymethylpentene". To achieve this desired floating condition, the 
wick-retaining recess is arranged at a level slightly below the peripheral 
portion of the wick-holder which is in contact with the surface when the 
wick-holder is floating. The peripheral portion of the wick-holder is 
joined to the wick-retaining recess by an arm disposed below the 
peripheral portion whereby in use the arm is submerged in the combustible 
oil. The recess for receiving the wick may be a through-hole or a blind 
hole, or may be formed by a tubular extension projecting up or down from 
the wick supporting portion. 
It is important to bear in mind that the candle holder does not float in 
water but in a layer of combustible oil which is less dense than water. 
Most plastics materials commonly used in injection moulding such as 
polystyrene, cellulose acetate or polypropylene are more dense than 
combustible oils and therefore require flotation chambers to be provided 
if they are to be used as floating wick-holders. For this reason flotation 
chambers have been used for a considerable time despite their disadvantage 
and despite the limitation which they place on the range of designs in 
which a floating candle can be made. Surprisingly, however, there is a 
plastics material available, poly-4-methylpent-1-ene, which has a 
sufficiently low density to enable it to be naturally buoyant in 
combustible oils. It is a comparatively high-melting material (MP = 
240.degree. C.) and its main field of application has been in the 
fabrication of shields for refrigerator light bulbs and the like products 
where a combination of transparency with good resistance to heat 
distortion is required. It was developed in the 1960's by Imperial 
Chemical Industries, was first marketed as long ago as 1965 by I.C.I. on a 
semi-commercial scale and its uses were reviewed by Rudolph D. Deanin, 
Society of Plastics Engineers Journal, 23 (2), 39-42 (1967). It has almost 
the minimum density for a thermoplastic material as appears from the 
following table taken from page 17 of "Polyolefin Plastics" by Theodore O. 
J. Kresser, Van Nostrand Reinhold Company, 1969: 
TABLE 
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Material Density 
______________________________________ 
Polyethylene - 
Low density 0.91 - 0.925 
Medium density 
0.926 - 0.94 
Linear 0.94 - 0.965 
Polypropylene - 
Homopolymer 0.902 - 0.906 
Copolymers 0.890 - 0.905 
Impact 0.90 - 0.91 
Polybut-1-ene 0.91 - 0.915 
Poly-4-methyl- 
pent-1-ene 
0.83 
Ethyl vinyl acetate 0.92 - 0.95 
copolymers 
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Despite its advantageous properties and low density, poly-4-methylpent-1ene 
has remained a comparatively small scale product and it is not mentioned 
except very briefly in the standard textbooks on plastics materials. It is 
not a well-known material. The sole supplier listed for the U.S.A. in 1975 
was the Mitsui Petroleum Company of Japan. The applicant herein is not 
aware of any publication or use of poly-4-methylpent-1-ene which takes 
advantage of its exceptionally low density or which takes advantage of its 
ability to float on combustible oil. 
As mentioned above poly-4-methylpent-1-ene is the only thermoplastic 
material which now exists which has a sufficiently low density to be used 
in this invention, but it is possible (though not likely) that other 
similar low-density materials may later be invented.

Referring to FIG. 1, a floating wick-holder is in the form of a one-piece 
member injection moulded from poly-4-methylpent-1-ene. The member has a 
central portion 1 formed with a through-opening 2 in which a wick 3 may be 
retained, and six disc-like main float portions 4 each of which is joined 
to the central portion by a respective one of six radiating arms 5. The 
main float portions 4 are located at a level higher than the upper surface 
of the central portion 1 so that when the member is set down the surface 
of a body of combustible oil, such as vegetable oil, the portions 4 float 
in the surface (indicated by broken line) and the portion 1 is beneath the 
surface. Consequently, there is no risk of the member coming into contact 
with the flame when the wick is alight. To prevent damage to the member 
when the supply of oil is nearly exhausted, it is preferred for the oil to 
be floated on the surface of a body of water which extinguishes the wick 
when the oil supply has been consumed. 
The embodiment shown in FIG. 2 is similar to that of FIG. 1, but the 
central and main float portions 1 and 4 have a shape such that, overall, 
the member has a floral appearance. In addition, the recess 2 for the wick 
is formed as a blind hole. 
In the case of the embodiment shown in FIG. 3, the member is formed as a 
spiral the hub 1 of which constitutes the wick supporting portion, while 
the turns 4 serve as the main float portion. Over at least a part of their 
overall length, the turns of the spiral form a spiral-helix so that when 
floated on oil the wick supporting portion and the inner turns lie below 
the surface of the liquid. 
The embodiment shown in FIG. 4 is similar to that of FIG. 3 but has a part 
annular main float portion 4. A wick supporting portion 1 is joined to the 
portion 4 by a single radial arm 5 which, together with the portion 1, 
lies beneath the plane of the portion 4. 
Modifications may of course be made to this embodiment it being possible to 
make the part 4 as a complete annulus and/or provide more than one arm 5. 
The embodiment shown in FIG. 7 is similar to that of FIG. 1 except that the 
float pads 4 have been omitted and the number of radiating arms 5 has been 
increased. The central portion 1 is formed with a blind recess 2a in its 
upper surface for supporting a wick and the arms extend radially therefrom 
to give a daisy or ox-eye appearance. The float pad is dished with a 
concave upper surface as is more clearly seen in FIG. 8 which shows the 
wick-holder of FIG. 7 in use in a lamp for table decoration. FIG. 8 shows 
a glass 7 containing a body of water 8 on which floats a relatively thin 
layer 9 of a combustible oil such as corn oil. The wick holder floats in 
the oil with its central portion 1 submerged but with a vertically 
disposed wick 3 protruding above the surface of the oil and with the 
radiating arms 5 submerged in the oil except for their ends which contact 
the surface. 
All of the embodiments of the wick holder described above, as well as 
others not disclosed but still making use of the same basic principle, are 
particularly suited to manufacture from plastics by injection moulding 
techniques.