Independent large-scale testing verifies that specifications for hydroseeding mulch should be written very clearly to distinguish between mulch made from paper and mulch made from wood chips. This distinction is based upon the respective performance capabilities of the two different types of mulches.

Once paper mulch is applied, it is basically a two-dimensional matrix, meaning it does not exhibit any significant vertical dimension, or loft. Paper lies flat on the ground, and it is not as effective as wood fiber mulch at holding moisture or preventing erosion. Once paper dries, it forms a “paper maché,” which is crusty and very difficult for young seedlings to grow through. Independent testing and years of experience in the field has taught us that paper should be limited to the tacking down of blown straw and for the seeding of flat or gently-sloped areas (less than 4H:1V) where an irrigation system is in place to keep the paper moist.

Wood fiber mulch, on the other hand, is derived from wood chips that are ground between large steel plates until the chips are converted to fine intertwined fibers. Furthermore, Profile® uses the superior thermal refining process, as opposed to an atmospheric refining process. The thermal refining process subjects 100% reused or recycled chips to high pressure steam prior to the steel grinding plates. Steam penetrates the wood chips and causes them to swell and expand, which yields more diverse and finer fibers than wood mulch created with an atmospheric refining process, which does not include the intermediate step of exposing the chips to high pressure steam. Once Thermally Refined® wood fiber mulch is applied, it provides a three-dimensional matrix on the ground surface, meaning it has a vertical dimension, or loft. The fine fibers, which have a high amount of surface area, hold more moisture than paper, which makes wood fiber mulch superior at establishing vegetation, especially where irrigation is not in place. In addition, the three-dimensional matrix of wood fiber mulch provides a better shield against the impact of rainfall and hail, and therefore is superior at preventing erosion.

Because paper doesn’t hold as much moisture, and doesn’t prevent erosion nearly as well as Thermally Refined wood fiber mulch, many states and provinces have prohibited the use of paper mulch. Large-scale independent testing has shown that paper mulch is only 25% effective at preventing erosion, whereas wood fiber mulch with no performance enhancing additives is 45% effective at preventing erosion. ASTM standard testing methods also indicate that wood fiber mulches are superior to paper at promoting vegetation establishment. In addition, where steeper or longer slopes exist, and where greater erosion protection is required (greater than 50% effective), there are advanced technologies, beyond basic paper and wood fiber mulches, that are indicated to ensure erosion prevention and vegetation establishment.

NOTE:

• Where erosion potential is present, wood fiber mulches should always be specified.
• Paper should not be allowed for use on slopes steeper than 4:1.
• Where greater than 50% erosion control effectiveness is desired, don’t allow the use of paper mulch OR base wood fiber mulch, but instead use SMM, BFM, FGM™ or ET-FGM (described in the following.)

Recommended Mulch Characteristics and Their Use

Wood Mulch
Materials: 100% wood fiber, made from thermally processed (within a pressurized vessel) wood fiber heated to a temperature greater than 380 degrees Fahrenheit (193 degrees Celsius) for 15 minutes at a pressure greater than 80 psi (552 kPa) and dark green marker dye.
Moisture Content: 12% +/- 3%
Water-Holding Capacity: 1,100% minimum
Approved Large-Scale Erosion Control Effectiveness: 45% minimum

When comparing the four base paper and wood mulches listed below, the key items to note are the differences in the maximum slope inclinations, slope lengths and the erosion prevention capabilities.

Cellulose (Paper) Mulch
Maximum slope inclination: 4:1
Appl. rate on maximum slope: 1,500-2,000 pounds/acre
Maximum slope length*: 18 feet
Functional longevity: up to 3 months
Erosion control effectiveness: 25%

Cellulose (Paper) Mulch with Tackifier
Maximum slope inclination: 4:1
Appl. rate on maximum slope: 1,500-2,000 pounds/acre
Maximum slope length*: 20 feet
Functional longevity: up to 3 months
Erosion control effectiveness: 30%

Wood Fiber Mulch
Maximum slope inclination: 2:1
Appl. rate on maximum slope: 3,000 pounds/acre
Maximum slope length*: 28 feet
Functional longevity: up to 3 months
Erosion control effectiveness: 45%

Wood Fiber Mulch with Tackifier
Maximum slope inclination: 2:1
Appl. rate on maximum slope: 3,000 pounds/acre
Maximum slope length*: 30 feet
Functional longevity: up to 3 months
Erosion control effectiveness: 50%

*Maximum slope length is based on a 4H:1V slope. For applications on steeper slopes, the maximum slope length may need to be reduced based on actual site conditions.

If greater than 50% erosion prevention effectiveness is desired, then the technologies should be specified and not the four base mulch products listed above.

Stabilized Mulch Matrix (SMM)
Maximum slope inclination: 2:1
Appl. rate on maximum slope: 3,500 pounds/acre
Maximum slope length**: 50 feet
Minimum cure time: 24 hours
Functional longevity: 3 to 6 months
Erosion control effectiveness: 90%

Bonded Fiber Matrix (BFM)
Maximum slope inclination: 1:1
Appl. rate on maximum slope: 4,000 pounds/acre
Maximum slope length**: 75 feet
Minimum cure time: 24 hours
Functional longevity: 6 to 12 months
Erosion control effectiveness: 95%

High Performance-Flexible Growth Medium™ (HP-FGM™)
Maximum slope inclination: > 1:1
Appl. rate on maximum slope: 4,500 pounds/acre
Maximum slope length**: 100 feet
Minimum cure time: 2 hours*
Functional longevity: 12 to 18 months
Erosion control effectiveness: 99.9%

Extended-Term Flexible Growth Medium (ET-FGM)
Maximum slope inclination: > 1:1
Appl. rate on maximum slope: 4,500 pounds/acre
Maximum slope length**: 125 feet
Minimum cure time: 2 hours*
Functional longevity: 18 to 24 months
Erosion control effectiveness: 99.95%

* HP-FGM and ET-FGM have very short cure times, and they can be applied onto wet soils and during a light rainfall.
** Maximum slope length is based on a 3H:1V slope. For applications on steeper slopes, the maximum slope length may need to be reduced based on actual site conditions.