If you fabricate and install
an HDU High Density Urethane sign according to manufacturer’s instructions, it
should last between 10 and 30 years. One of the keys to creating a durable HDU sign
is using adhesives, texturing materials, primers and paints which are
compatible with the signboard. That’s why I selected the Precision Board
materials by Coastal Enterprises. They have a complete system of products
matched for compatibility. What’s more, if you have questions, they have the
service organization that provides prompt, reliable answers.
an HDU High Density Urethane sign according to manufacturer’s instructions, it
should last between 10 and 30 years. One of the keys to creating a durable HDU sign
is using adhesives, texturing materials, primers and paints which are
compatible with the signboard. That’s why I selected the Precision Board
materials by Coastal Enterprises. They have a complete system of products
matched for compatibility. What’s more, if you have questions, they have the
service organization that provides prompt, reliable answers.
Two best glues to use when gluing High Density Urethane are polyurethane
(urethane) glue and epoxy resin glue. The most popular urethane glue on the
market is the original Gorilla Glue. Today the Gorilla Glue company
manufactures many different types of glues.
(urethane) glue and epoxy resin glue. The most popular urethane glue on the
market is the original Gorilla Glue. Today the Gorilla Glue company
manufactures many different types of glues.
I have used Gorilla Glue and the urethane glue that
Coastal Enterprises sells when gluing multiple sheets of High Density Urethane
together to make one thick block for carving. In the picture below, I have glued four sheets
of HDU together and then rough cut the shape with a sawzall Reciprocating Saw. See the photo below.
Coastal Enterprises sells when gluing multiple sheets of High Density Urethane
together to make one thick block for carving. In the picture below, I have glued four sheets
of HDU together and then rough cut the shape with a sawzall Reciprocating Saw. See the photo below.
Reciprocating saw or Sawzall can help to rough out a carving. |
● A coarse reciprocating blade easily rough cuts a thick
block of HDU.
block of HDU.
● When rough cutting a block of HDU clamp the block to
the work surface.
the work surface.
Milwaukee Super Sawzall Reciprocating Saw |
● The Original Sawzall on
the market.
the market.
● Rated the strongest most powerful sawzall.
● Works with a variety of
blades covering a range of construction and demolition applications.
blades covering a range of construction and demolition applications.
● Great for trimming
branches.
branches.
● Rugged construction for years of reliable performance.
I then shaped the
block using gouges to create my Japanese Oni mask shown below. To the top of
this head I will glue horns. For that application, I will use an epoxy
adhesive.
The Original Gorilla Glue
has a number of great features:
has a number of great features:
● It has tremendous bonding
power.
power.
● It is 100% waterproof, so
it is a great for building outdoor HDU signs.
it is a great for building outdoor HDU signs.
● Using water activates the
glue so it expands to fill any minor gaps between boards.
glue so it expands to fill any minor gaps between boards.
Bonding
HDU Boards Together Using Urethane Glue
What’s
nice about polyurethane adhesive is that there is no measuring. To activate the
urethane glue you just need to moisten the surface to be bonded by lightly
spraying the HDU with water, then clamp the pieces and you are done. More water is not better, so wipe off any
excess water with your hand.
nice about polyurethane adhesive is that there is no measuring. To activate the
urethane glue you just need to moisten the surface to be bonded by lightly
spraying the HDU with water, then clamp the pieces and you are done. More water is not better, so wipe off any
excess water with your hand.
In
creating a Tiki head for a sign, I glued sheets of HDU together. Prior to
gluing the pieces together, make sure that the surfaces fit tightly so you do
not have any gaps.
creating a Tiki head for a sign, I glued sheets of HDU together. Prior to
gluing the pieces together, make sure that the surfaces fit tightly so you do
not have any gaps.
After
the surfaces are moistened, apply a thin coating of urethane glue using an
inexpensive squeegee. As you spread the adhesive, squeegee the excess to the
center of the board. By doing this, you this technique will prevent air pockets
from being trapped between the boards.
the surfaces are moistened, apply a thin coating of urethane glue using an
inexpensive squeegee. As you spread the adhesive, squeegee the excess to the
center of the board. By doing this, you this technique will prevent air pockets
from being trapped between the boards.
After
the urethane glue is applied, position one board over another. Apply weights to
the top of the boards so that the pressure is evenly distributed. See the photo
below. Using these weights alone is not sufficient to hold the boards in place.
To keep them from slipping and sliding out of place, toe nail the boards
together in several places with drywall screws.
the urethane glue is applied, position one board over another. Apply weights to
the top of the boards so that the pressure is evenly distributed. See the photo
below. Using these weights alone is not sufficient to hold the boards in place.
To keep them from slipping and sliding out of place, toe nail the boards
together in several places with drywall screws.
Urethane glue can expand
near four times their original volume. In a couple of minutes the adhesive will
start to bubble. Keep the surfaces
clamped for at least four hours. Full curing occurs after 12 hours. You can
expect some squeeze out. Remove the residual adhesive with either a razor or a
#3 woodcarving gouge.
near four times their original volume. In a couple of minutes the adhesive will
start to bubble. Keep the surfaces
clamped for at least four hours. Full curing occurs after 12 hours. You can
expect some squeeze out. Remove the residual adhesive with either a razor or a
#3 woodcarving gouge.
If you have not worked with
urethane glues, be advised that they are messy. For this reason wear latex
gloves and your grubbiest clothes. Also cover your work table with application
tape for easy clean up. Placing sheets of wax paper or clear application tape
underneath the glued pieces prevents gluing your HDU project to your work
surface.
urethane glues, be advised that they are messy. For this reason wear latex
gloves and your grubbiest clothes. Also cover your work table with application
tape for easy clean up. Placing sheets of wax paper or clear application tape
underneath the glued pieces prevents gluing your HDU project to your work
surface.
Gluing with Epoxy Adhesive
While signs made from HDU
have a number of advantages over redwood and cedar, one disadvantage, is that
it has neither the density nor structural strength of wood. As a comparison,
the density redwood is about 27 lb. per cubic foot, which is nearly twice that
of 15 lb. HDU.
have a number of advantages over redwood and cedar, one disadvantage, is that
it has neither the density nor structural strength of wood. As a comparison,
the density redwood is about 27 lb. per cubic foot, which is nearly twice that
of 15 lb. HDU.
Whereas wood is comprised of
long, sinewy fibers, HDU is made up of very tiny cells – bubbles, if you will,
that are formed in the chemical foaming process. These little bubbles don’t
provide a lot of structural strength.
long, sinewy fibers, HDU is made up of very tiny cells – bubbles, if you will,
that are formed in the chemical foaming process. These little bubbles don’t
provide a lot of structural strength.
If a sign is subjected to
significant wind load, you must support the HDU board in some way to strengthen
the panel. For the background of my Tiki Bar sign I used a one and a half inch
sheet of HDU, which I carved into as much as an inch deep in some places. That
didn’t leave me with much bulk the sheet.
I felt that I needed extra strength so I laminated a 2’ x 4’ sheet of
aluminum composite panel (otherwise known as Dibond) to a sheet of HDU of the
same size. For this application the Dibond was a better choice than wood or
MDO, because it is not only lighter weight but more importantly it is more
dimensionally stable.
significant wind load, you must support the HDU board in some way to strengthen
the panel. For the background of my Tiki Bar sign I used a one and a half inch
sheet of HDU, which I carved into as much as an inch deep in some places. That
didn’t leave me with much bulk the sheet.
I felt that I needed extra strength so I laminated a 2’ x 4’ sheet of
aluminum composite panel (otherwise known as Dibond) to a sheet of HDU of the
same size. For this application the Dibond was a better choice than wood or
MDO, because it is not only lighter weight but more importantly it is more
dimensionally stable.
A urethane adhesive would
have worked, but epoxy adhesive provides better structural strength and is
great for bonding HDU to wood, plastic or metal.
have worked, but epoxy adhesive provides better structural strength and is
great for bonding HDU to wood, plastic or metal.
The West System Epoxy is
comprised of three components: the 105 resin, a hardener and, often when used
as an adhesive, a filler. The key ingredient in any of these formulations is
the West System 105 resin. Depending on which hardener and filler you select,
you can use it to as an epoxy glue, or as a clear coat or for laminating
fiberglass cloth or to repair damage to a surface.
comprised of three components: the 105 resin, a hardener and, often when used
as an adhesive, a filler. The key ingredient in any of these formulations is
the West System 105 resin. Depending on which hardener and filler you select,
you can use it to as an epoxy glue, or as a clear coat or for laminating
fiberglass cloth or to repair damage to a surface.
West System 105 Epoxy Resin
|
For my project I
selected the West System 205 Fast
Hardener. If you need additional working time, especially when working in
warmer environments, use the West System 206 Slow Epoxy Hardener. For coating a
bar top or wood project, you can use the West System 207 Special Coating
Hardener.
selected the West System 205 Fast
Hardener. If you need additional working time, especially when working in
warmer environments, use the West System 206 Slow Epoxy Hardener. For coating a
bar top or wood project, you can use the West System 207 Special Coating
Hardener.
What’s important when
working with any epoxy system is that the resin and the hardener are mixed in
the correct proportions. If you happen to mess up the mixture ratios, the resin
will not cure and you will end up with a mess on your hands.
working with any epoxy system is that the resin and the hardener are mixed in
the correct proportions. If you happen to mess up the mixture ratios, the resin
will not cure and you will end up with a mess on your hands.
Metering out the right
proportions is not difficult if you use the West System 300 mini pumps. All you
need to remember is to combine one full pump of resin with one full pump of
hardener.
proportions is not difficult if you use the West System 300 mini pumps. All you
need to remember is to combine one full pump of resin with one full pump of
hardener.
West System 205 Hardener
|
After
dispensing the two components in a clean container, you must thoroughly mix the
West System Epoxy resin and hardener together. Whenever you mix any components,
make sure that you scrape the sides and the corner at the bottom of the
container.
dispensing the two components in a clean container, you must thoroughly mix the
West System Epoxy resin and hardener together. Whenever you mix any components,
make sure that you scrape the sides and the corner at the bottom of the
container.
To
change the consistency of the resin/hardener mixture, you can add filler. It
can also be used as an extender. Selecting the right filler for your
application is the confusing part of using epoxies because there are so many
products from which to choose. I used the West System Microfiber Filler, which
consists of microfibers of chopped cotton. Using this filler creates a good
multi-purpose adhesive.
change the consistency of the resin/hardener mixture, you can add filler. It
can also be used as an extender. Selecting the right filler for your
application is the confusing part of using epoxies because there are so many
products from which to choose. I used the West System Microfiber Filler, which
consists of microfibers of chopped cotton. Using this filler creates a good
multi-purpose adhesive.
West System MICROFIBERS – 20
OZ |
If the surfaces are uneven, a
filler also produces a mixture that will fill any gaps. The high density
fillers, such as West System’s 405 or 406, change the structural
characteristics of the epoxy, making it either stronger or thicker. These high
density fillers become very hard after the epoxy cures, which makes sanding
difficult. The different fillers can be mixed together to produce your own
special concoction.
filler also produces a mixture that will fill any gaps. The high density
fillers, such as West System’s 405 or 406, change the structural
characteristics of the epoxy, making it either stronger or thicker. These high
density fillers become very hard after the epoxy cures, which makes sanding
difficult. The different fillers can be mixed together to produce your own
special concoction.
In thickening epoxy, add
small amounts of the filler, little by little, until you produce the desired
consistency. For laminating flat panels of HDU and aluminum composite panel,
you will want the epoxy to have the consistency of ketchup.
small amounts of the filler, little by little, until you produce the desired
consistency. For laminating flat panels of HDU and aluminum composite panel,
you will want the epoxy to have the consistency of ketchup.
Safety Recommendations.
While epoxy poses little potential for respiratory problems, you should work in
a clean, well-ventilated shop. It also
would not hurt you to wear a respirator with an organic vapor canister. Contact
with your skin can result in dermal reactions such as skin irritation, rashes
and allergic dermatitis. For this reason, always wear the chemical-resistant
gloves, clothing and other safety gear recommended by the manufacturer. If you
are sanding, wear a respirator with a particulate filter.
While epoxy poses little potential for respiratory problems, you should work in
a clean, well-ventilated shop. It also
would not hurt you to wear a respirator with an organic vapor canister. Contact
with your skin can result in dermal reactions such as skin irritation, rashes
and allergic dermatitis. For this reason, always wear the chemical-resistant
gloves, clothing and other safety gear recommended by the manufacturer. If you
are sanding, wear a respirator with a particulate filter.
Guidelines for Working with
Epoxy
When bonding one surface to
another with epoxy adhesive you need to follow a few guidelines:
another with epoxy adhesive you need to follow a few guidelines:
● Because there are time limitations when working with epoxy
glue, make sure that you assemble all of the materials and equipment that you
need for the job. Take into consideration, that when you would with larger
batches or thicken an epoxy with filler,
you increase the mass of the mixture generating more heat, which shortens the
pot life.
glue, make sure that you assemble all of the materials and equipment that you
need for the job. Take into consideration, that when you would with larger
batches or thicken an epoxy with filler,
you increase the mass of the mixture generating more heat, which shortens the
pot life.
● Test, Don’t Guess. As a
word of caution, if you are bonding two different types of materials it is best
to test the bond strength of the dissimilar materials prior to fabrication.
While epoxy glue sticks to just about anything, there are some low energy
plastics, such as polyethylene, that it will not stick to.
word of caution, if you are bonding two different types of materials it is best
to test the bond strength of the dissimilar materials prior to fabrication.
While epoxy glue sticks to just about anything, there are some low energy
plastics, such as polyethylene, that it will not stick to.
● Make sure the surfaces are
dry.
dry.
● In storage and during
fabrication, the surface of the HDU can accumulate dirt and dust. To clean the
surface, slightly abrade the surface with a grey Scotch-Brite pad. Before applying the epoxy adhesive, brush off
any residue from the surface using a chip brush and wipe it down with a clean
rag. Contaminants will compromise the adhesive bond.
fabrication, the surface of the HDU can accumulate dirt and dust. To clean the
surface, slightly abrade the surface with a grey Scotch-Brite pad. Before applying the epoxy adhesive, brush off
any residue from the surface using a chip brush and wipe it down with a clean
rag. Contaminants will compromise the adhesive bond.
● When bonding to a
non-porous smooth surface, such as the aluminum composite panel, rough it up
with 80-grit sand paper. This will give the surface some tooth so the adhesive
bonds to it.
non-porous smooth surface, such as the aluminum composite panel, rough it up
with 80-grit sand paper. This will give the surface some tooth so the adhesive
bonds to it.
● To bond the HDU and the
Dibond panel, used a two-step procedure. First, I coated the HDU with epoxy
without any filler using a foam roller. This ensures that the epoxy adhesive
wets out the entire surface of the HDU.
Dibond panel, used a two-step procedure. First, I coated the HDU with epoxy
without any filler using a foam roller. This ensures that the epoxy adhesive
wets out the entire surface of the HDU.
● Right after applying this
first coating, pour the epoxy glue thickened with the filler onto the HDU. If
you are covering a fairly large surface pour the thickened epoxy in the middle
of the panel and spread it evenly using a notched spreader. You do not need
much adhesive to create a great bond. This type of spreader applies a uniform
thickness of epoxy adhesive and prevents air pockets from developing in your
lamination.
first coating, pour the epoxy glue thickened with the filler onto the HDU. If
you are covering a fairly large surface pour the thickened epoxy in the middle
of the panel and spread it evenly using a notched spreader. You do not need
much adhesive to create a great bond. This type of spreader applies a uniform
thickness of epoxy adhesive and prevents air pockets from developing in your
lamination.
● After coating epoxy
adhesive to one panel, laminate the two panels together using moderate pressure
– just enough for the thickened adhesive to start squeeze out. An alternative
to using clamps to secure the panels as the epoxy cures is to use drywall
screws and weights evenly distributed over the panel. Too much clamping
pressure will squeeze out too much of the adhesive to from a good bond. It is
critical that you maintain pressure the two parts to be joined until the
epoxies cures, which is generally about eight hours. Failure to maintain
consistent pressure may result in the parts pulling apart, which will stress
the bond.
adhesive to one panel, laminate the two panels together using moderate pressure
– just enough for the thickened adhesive to start squeeze out. An alternative
to using clamps to secure the panels as the epoxy cures is to use drywall
screws and weights evenly distributed over the panel. Too much clamping
pressure will squeeze out too much of the adhesive to from a good bond. It is
critical that you maintain pressure the two parts to be joined until the
epoxies cures, which is generally about eight hours. Failure to maintain
consistent pressure may result in the parts pulling apart, which will stress
the bond.
● Clean up any of the
adhesive squeeze out, as best you can, before it hardens.
adhesive squeeze out, as best you can, before it hardens.
Pot Life and Working Time
Pot life and working times
for epoxy glue can vary greatly based on the temperature of your shop. The
warmer the temperature is, the faster the epoxy cures. At 72°F (22°C) pot life
for a mixture can as little as 10 minutes. At 90°F (32°C) that time is cut in
half. That means that if you are working on a hot day, you better work fast!
for epoxy glue can vary greatly based on the temperature of your shop. The
warmer the temperature is, the faster the epoxy cures. At 72°F (22°C) pot life
for a mixture can as little as 10 minutes. At 90°F (32°C) that time is cut in
half. That means that if you are working on a hot day, you better work fast!
It case you don’t know what
pot life is, it is the amount of time that it takes for resin and hardener to
cure in your mixing cup before it hardens. Working time, on the other hand, is
the time it takes for resin to cure after it is spread out onto the surfaces
that you are trying to bond. Depending on the ambient temperature, you can have
as much as an hour for working.
pot life is, it is the amount of time that it takes for resin and hardener to
cure in your mixing cup before it hardens. Working time, on the other hand, is
the time it takes for resin to cure after it is spread out onto the surfaces
that you are trying to bond. Depending on the ambient temperature, you can have
as much as an hour for working.
Curing to a hardened state
can take as much as 6 to 8 hours. Complete curing takes even longer. In about
two weeks, epoxy adhesive is nearly at full strength. (Don’t be concerned if the
adhesive on a test panel feels tacky before it cures completely. Epoxy adhesive
should harden as solid as a rock, if you follow the manufacturer’s directions.)
can take as much as 6 to 8 hours. Complete curing takes even longer. In about
two weeks, epoxy adhesive is nearly at full strength. (Don’t be concerned if the
adhesive on a test panel feels tacky before it cures completely. Epoxy adhesive
should harden as solid as a rock, if you follow the manufacturer’s directions.)
So why is there such a
difference between pot life and working time? Mixing resin and hardener creates
a chemical reaction that creates heat. In a confined space such as a mixing
cup, you contain the heat. When you do that, the heat builds up really fast. In
fact, you can feel the heat as you are holding the mixing cup. In most cases it
is better to mix multiple smaller batches than one big batch.
difference between pot life and working time? Mixing resin and hardener creates
a chemical reaction that creates heat. In a confined space such as a mixing
cup, you contain the heat. When you do that, the heat builds up really fast. In
fact, you can feel the heat as you are holding the mixing cup. In most cases it
is better to mix multiple smaller batches than one big batch.
When you pour the mixed
epoxy glue onto your working surface, the heat dissipates. Using the example of
bonding Dibond aluminum composite material to the Precision Board HDU, the
metal surface can dissipate the heat fast. On the other hand, the HDU does not
dissipate the heat so fast.
epoxy glue onto your working surface, the heat dissipates. Using the example of
bonding Dibond aluminum composite material to the Precision Board HDU, the
metal surface can dissipate the heat fast. On the other hand, the HDU does not
dissipate the heat so fast.
So what can you do? If it is
impractical or impossible to control the temperature of your work environment,
the simplest solution is to use a slow hardener. If you are mixing on a large
surface, you can mix smaller batches until the surface is completely covered.
impractical or impossible to control the temperature of your work environment,
the simplest solution is to use a slow hardener. If you are mixing on a large
surface, you can mix smaller batches until the surface is completely covered.
About Jim Hingst: After fourteen years as Business Development Manager at RTape, Jim Hingst retired. He was involved in many facets of the company’s business, including marketing, sales, product development and technical service.
Hingst began his career 42 years ago in the graphic arts field creating and producing advertising and promotional materials for a large test equipment manufacturer. Working for offset printers, large format screen printers, vinyl film manufacturers, and application tape companies, his experience included estimating, production planning, purchasing and production art, as well as sales and marketing. In his capacity as a salesman, Hingst was recognized with numerous sales achievement awards.
Drawing on his experience in production and as graphics installation subcontractor, Hingst provided the industry with practical advice, publishing more than 150 articles for publications, such as Signs Canada, SignCraft, Signs of the Times, Screen Printing, Sign and Digital Graphics and Sign Builder Illustrated. He also posted more than 400 stories on his blog (hingstssignpost.blogspot.com). In 2007 Hingst’s book, Vinyl Sign Techniques, was published. Vinyl Sign Techniques is available at sign supply distributors and at Amazon.