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Frequently Asked Questions
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What is "standard
low density"?
Low density
polyethylene (LDPE) is the most versatile choice for a wide range of
packaging needs, and for that reason, it is the material from which most of
our stock poly bags and film are made. Low density is has excellent clarity
and strength, and has adequate substance to protect most items it covers. |
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What
is "clarity" resin?
Clarity
is the degree to which a film is transparent and clear of clouding. Resins
are manufactured to match a profile, and that profile predicts its extrusion
performance across a range of behaviors. One of the elements in a profile is
haze, and when high clarity is critical to the display of a product, we can
manufacturer your film from resin with a low haze. |
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What is "linear low
density"?
Linear low density
polyethylene (LLDPE) film has a molecular configuration that lends it to
applications where strength, and puncture strength in particular, is more
important than clarity. LLDPE films tend to stretch more than low density
films before breaking, though they are typically lighter and provide less
barrier protection. |
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How do "hexene", and "octene"
LLDPE differ?
We offer standard LLDPE film from a blend of high-grade resins.
However, bags and film can also be manufactured from pure hexene or octene
resin. Hexene is a very strong LLDPE material, and will stand up to more
rigorous demands than a standard blend. Octene is the preeminent LLDPE
resin, and delivers the highest performance at a given weight of any LLDPE
material. |
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What is does gauge
"equivalent" mean?
There are
many kinds of plastic from which bags and film can be made, and they each
have their own characteristics regarding tear strength, tensile strength,
puncture resistance, clarity, weight, shielding, and so on. Low density
polyethylene is generally considered the most versatile and reliable
material across the full range of film properties. In an effort to lower
costs, however, claims are sometimes made that alternate materials can act
as a good "equivalent" to a low density resin. It may be said, for
instance, that a .0015 gauge linear density bag is an "equivalent"
to a .002 gauge low density bag in terms of strength. We are happy to
manufacture bags in either low density or linear low density. However, it is
generally better to match a user's needs to a material, understanding all of
its properties and behaviors, and avoid seeking equivalents. Different
plastics are only equivalent in a very narrow sense of the word. |
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What does
"anti-static" mean?
Anti-static bags and film are intended to reduce the risk of shock to
static-sensitive products and components. |
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What
are "pink", "Purestat" and "non mil
spec" anti-static?
Pink has traditionally been used in bags and tubing as a visual cue that a
film has anti-static properties. The static protection in this film is
provided by amines, which create a kind of film on the inside of a bag or
tubing. Purestat is typically clear, and provides its anti-static protection
without the use of amines.
Mil-specs correspond to military standards for film behavior. When extruded
in .004 mil, for instance, pink anti-static film meets the static decay rate
of MILB81705 Type II, whereas .006 mil Purestat meets the electrical
requirements of the same mil-spec. Only pink anti-static bags and film of
.006 mil meet the full MILB81705 Type II specification.
Non-mil spec bags and film are not related to any military specification.
The anti-static element is present primarily to make bags easier to open,
and will not protect products from static charge. |
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What is EVA?
When EVA, or ethyl-vinyl acetate, is present as 2-3% additive to a
polyethylene resin, it can make a bag considerably stronger. EVA is often
used in applications where a bag or film will be frozen, and helps the film
resist cracking. |
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What is
"anti-block"?
Anti-block is
an additive that may reside in polyethylene resin or be mixed with a resin
to alter its performance. When polyethylene resin is extruded, anti-block
bleeds to the inside of the bags and increases the ease with which bags
open. |
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What does
"non-scratch" mean?
Non-scratch bags and film contain little or no anti-block additive. This
additive, when it bleeds to the inside of a bag, may appear as a fine powder
capable of scratching very delicate products. Because anti-block also makes
the inside of bags slippery, however, non-scratch bags and tubing will be
very difficult to open. |
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What is "slip'?
Slip is an additive that may reside in polyethylene resin or be mixed with a
resin to alter its performance. When polyethylene resin is extruded, slip
bleeds to the outside of the bags and increases the degree to which they
slip, or glide. Slip makes bags easy to handle and prevents them from
sticking to one another. High slip bags call for extra slip additive which
increases the degree to which bags glide in any given process or handling,
whereas low slip bags inhibit movement and promote grip. |
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What is the difference
between "transparent" and "opaque"?
Transparent bags are see-through, regardless of their color, whereas opaque
bags cannot be seen through. In both cases, light can pass through the film. |
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How do you size a bag to
a square or rectangular container?
1. Add the width and length of the sides. Add 2 in.
for a looser fit. This total equals the flat width of the bag needed.
2. Add ½ of the shortest side to the height of the
container. Add 5 in. to this value for overhang. This equals the length of
the bag.
3.
If tying bag, rather than lining box, add ½ the
length of the shortest side to the bag length in #2.
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How do you size a bag to
a round container?
1. For the
circumference of the bag, multiply the diameter of the container by
3.14. Divide by 2 to get the flat width. Add 1 in. for a looser fit.
2. Add ½ of the
diameter to the height of the container. Add 5 in. to this total for
overhang. This is the total length of the bag needed.
3. If tying bag,
rather than lining container, add ½ the diameter to the bag length in
#2. |
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How should I inspect bag
gauge?
Keep in mind that polyethylene
is a flexible material, and that gauge can only be measured with a poly
micrometer. Machine micrometers, intended for less delicate materials, pinch
and flatten bags or film. Ultimately, even poly micrometers offer only a
rough measure, as gauge will naturally vary across the width of any bag or
film. This is inherent to the extrusion process. The best way to see if you
are getting what you expect from any manufacturer is to compare your case
weights to a properly calculated yield. Our appropriate case weights are
provided with each product listing. Case weights are the best indication of
how much plastic your getting in a given bag count. |
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Are
your bags
recyclable?
All of our low density bags
are recyclable. To find out whether your recycling plant accepts low density
bags, look for the national recycling symbol encircling the number 4. Number
4 is the Society of Plastics Industry code for LDPE (Low Density
Polyethylene). |
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