HDU Signs
HDU (High-Density-Urethane) This material was originally created to be used in the aerospace industry. It can be found in almost every automobile that is built today, it fills the wings of airplanes and can be found between the 9" thick steel plates that make up the hulls of nuclear submarines. It is a very versatile material. It is resistant to most chemicals and solvents; any type of paint can be used on it.
Chickahominy Falls is a 4" thick HDU sign created with a combination of hand carving, routing. sandblasting and appliqued routed letters. Our client wanted it to have the look of a slab of rough-hewn sandstone with perfectly smooth-shaped letters rising out of it. To see how this was created follow this link Chickahominy blog
HDU is a very "Green" material
HDU. is both artist- and environmentally friendly. Not only does it save trees as an optimal wood replacement, but it is also sustainably produced, with a minimum of 16 percent green content. In fact, every sheet contains 240 recycled plastic water bottles. So, this material is better for your work, better for the earth, and better for your health. What's more, this eco-friendly solution can contribute LEED certification points for building credits. HDU. is nontoxic, U.S.-made, VOC, and CFC-free.
If HDU is sandblasted it has the look of a stone texture which is great for detail signs but if we sandblast it through a frame of piano wire we can create what looks just like the wood grain you get from a sandblasted all heart vertical grain redwood sign. Click on the photo above and you will see the two textures used together on the Square Pond sign
This HDU sign was epoxied together to a thickness of 3" and has the faux wood grain effect
HDU is a very "Green" material (cont)
It is impermeable by water and moisture, and unaffected by high-salt environments. And, the material is formulated to withstand temperatures from −30° F to 220°F. So it holds up under extreme conditions and in severe weather. HDU. clearly outperforms wood.
Village Chapel in Pinehurst NC is a colonial pediment-style monument sign manufactured completely from HDU. The bottom panel with the service times is removable.
Positives
- This material has zero moisture content, so unlike wood when it heats up in the sun there is no moisture to expand and cause blisters that will crack in cold weather and start the breakdown process of the paint or whatever coating is applied.
- It has a very low "expansion/contraction factor". This means that it doesn't expand in the heat causing the paint to crack; allowing more water (or humidity; same thing) to start the downward spiral of destruction.
- It will not warp (without any outside influences), crack or check.
- There is no color or stain to bleed through the paint causing discoloration.
- It is very easy to cut, route, carve, sandblast and shape.
- As long as it is kept painted, it will last indefinitely.
Calvert City sign
This city entrance sign is sandblasted HDU and is 12 feet wide, which means that the total width of the monument is over 40 feet. What is unusual about this is that the capstones all the way across are also made from HDU. It was built in our workshop and taken out in our trailer in 6 pieces where we supervised the installation by our client's own employees.

Negatives
- It doesn't smell like redwood or cedar
Bethesda Church sign is a 12' x 12' x3" thick HDU sign, It was built from two halves and has a 2" x 0.25" thick steel skeleton running horizontally and vertically all welded together and epoxied into routed pockets in the center of the sign so that when it was epoxied together it isn't seen except at the sides where it is used to mount the sign. This means any stresses are on the steel and not on the sign itself.
Things to be aware of.
It is important to use the right HDU, as in everything there are many manufactures of the product, and not all HDU is created equal. The cheaper HDU brands are much more likely to crack under pressure or stress. Many sign manufacturers tell their customers there is no difference between one sheet of HDU and another sheet by a different manufacturer. That is NOT TRUE. Many of the cheaper sheets are brittle and can be easily damaged. You get what you pay for, if someone is selling at a very low price it is probably too good to be true different brands from different wholesalers can differ by over $250.00 per sheet
Below are two sets of relevant links to other pages on this site that may be helpful to you.
Directly below are links to other pages on different types of dimensional signs and below that are links to photo galleries relating to those types of signs.
- HDU signs (this page)
- Sand Blasted sign
- carved and routed 3-dimensional signs
- Sandblasted redwood signs
- Sandblasted wooden signs
- Prismatic letters on sandblasted signs
- Sandblasted signage
- Hand-carved signs
- 23kt Gold leaf sign picture gallery
- Sandblasted Signs Gallery
- Monument Sign Gallery
- Sandblasted Wooden Signs Gallery
- Routed and carved sign picture gallery
- Community and subdivision signs gallery