Backpack Material Delamination
Over a long period of time all synthetic laminated backpack materials
are prone to the delaminating of the Polyurethane (PU) Coating.
This can occur naturally or be hasten by exposure of the Polyurethane
Coating to direct sunlight for long periods, heat and high humidity,
harsh chemicals used to clean the backpack, long periods of exposure
to salt water, exposure to swimming pool chlorine (rinse well immediately
and dry thoroughly by hanging in a shady area after immersion in
seawater or exposure to chlorine), or long periods of storage in
either damp or occasionally damp areas, particularly on cement floors.
When put in storage the backpack must be 100% dry and preferably
stored hanging in a cool shaded area so air can circulate around
the backpack. Storing your pack while it is damp will cause the
Polyurethane Coating to soften become sticky and stick to itself
(a chemical reaction called hydrolysis). With prolonged exposure
to moisture, the coating will flake and peel away from the fabric
and create leakage.
All Polyurethane Coated synthetic backpacks with material lamination
will eventually fail. Generally most backpacks will have worn out
before delimitation takes place. However, with a good quality backpack
this isn’t the case. Removing the flaky delaminated PU coating can
be done quite easily and the material can reproofed with NIKWAX
'Tent & Gear SolarProof®' Waterproofing.
A little common sense will prevent premature aging of the synthetic
material's Polyurethane Coating. Always clean and dry your backpack
before you put it away. Never pack or store you’re a backpack if
it is dirty or damp. Wet synthetic material can mildew which causes
corroded zippers, delaminating, leaks, and foul smells. There is
no cure for delaminating and severe mildew damage.
Mildew damage and hydrolysis (delaminating) are not covered by
the White Mountain™ Lifetime Warranty.
PU coated fabric is made up of a synthetic woven base fabric
(usually polyester or nylon) with a waterproofing Polyurethane Coating
or laminate. The polyurethane coating is applied to a single side
of the base fabric, this makes the fabric water resistant, light
weight, and flexible. Applications include: camping tents, light
duty covers, clothing, bags, and backpacks.
Wholesalers and manufacturers see PU Coatings as having a limited
lifespan, and do not guarantee for life the integrity of fabric
coatings, and neither can White Mountain™ Backpacks. The good news
of coatings peeling is the fabric strength usually increases - and
in wet weather rain covers are generally recommended. Many things
can have an impact on the life of PU Coatings just as environmental
factors affect foam. Moisture (dry your backpack well after wet
weather), mould, excessive heat (this may apply to tropical climates,
especially with high humidity), and chemical contamination (harsh
cleaning products, salt water, and chlorinated pool water to name
a few) can contribute to the break down or delaminating of the PU
Coating. Also, these PU Coatings will wear off over time; anywhere
between 5-15 years depending on the use and care of the product.
To extend the life of the PU Coating, always store backpacks in
well ventilated areas and take care of these PU Coated products
as you would anything valuable.
It is important to remember that the deteriorating of the PU
Coating over time does not mean your backpack requires replacing,
and this event is expected with all PU Coated materials. We have
listed some suggestions for restoring the water proofing of your
backpack in the following, however, please note we cannot take responsibility
for any mishaps that may occur using these techniques.
Having tested an ironing technique we have found it basically
works in arresting the continual delaminating of PU material in
a backpack. Use a modern iron on synthetic (the iron just does not
need to be that hot) on DRY (no steam) and ironing the affected
area through two (2) sheets of 80gsm copy paper it does seem to
do the trick. However, any very loose material will strip away from
the material and stick to the paper (it is very important NOT to
over iron and to NOT over heat any one area). Better to do it briefly
throughout the affected area ironing just past where the delaminating
begins. This needs to be done very carefully and the iron should
never make contact with the material directly (there is a risk of
melting the material), or be in contact with the one area of the
material for very long (will heat all the laminate to a point where
it adheres to the paper). Finish by spraying the coated face of
the fabric with a silicon or Teflon based water repellent.
After treating your backpack to arrest the delaminating of the
PU coating we recommend using NIKWAX 'Tent and Gear SolarProof®'
Customer Response to this Repair Technique
I have followed the procedure you suggested and it has worked
a treat - I'm really pleased with the result. Some of the seams
were quite hard to get to so I used a hair drier and just gave the
heated areas a squeeze with fingers. There was enough heat to laminate
the film back onto the fabric without burning fingers. The edges
of the pen pockets were just starting to shed so I used the hair
dryer on this as well. All in all an excellent outcome!
Repair Severe Delamination and Reproof Backpack
First remove all the delaminated PU coating. We have found that
using a stiff brush on a vacuum cleaner works very well with
wholly deteriorated and fully flaking PU coating, and stops
the delaminated PU coating from spreading and sticking to everything. Make
sure you get under all the seams and thoroughly remove all the delaminated
If some of the delaminated PU coating is more persistent and
still adheres to the backpack, we have found that wiping with
inexpensive white vinegar removes the delaminated PU coating
with ease on nylon and polyester material with great success.
With stubborn and difficult to remove PU coating or when
removing the PU coating from textured material we have found
that using Isopropyl Alcohol is the better option, although this
is a more expensive solution. Using a nail brush on textured
material is recommended to assist in the removal of PU coating
that is difficult to remove, and using a tooth bush in the seams
may also make the removal process easier.
Make sure you wipe
down the cleaned material thoroughly with a water dampened cloth
and leave to dry before reproofing.
After cleaning off all the PU and making sure the backpack material is
thoroughly clean and dry apply the NIKWAX
'Tent and Gear SolarProof®' Waterproofing. We have had great success
with this, and you need to carefully follow the instructions provided.
Remember a little goes a long way and there is no need to saturate
the material, simply apply a light spray on the material and wipe
the excess spay away with a damp cloth. Also, the instructions recommended
spraying the outside of the material, however we had great success
spraying the inside, the reverse side of the material.
This can be a time consuming process, however with some
effort you will restore your backpack to as new condition, and your backpack material should now be as waterproof as it was