L1.S. Deprtnmt of Agriculture

Forest Se-ruice Research Note S E - 3 04 February I9SI

NEW PLASTIC APRON-GUTTER FOR GUM COLLECTION

Ralph W. Clements’

and

H. Grady Williams*

ABSTRACT-A one-piece polyethylene apron-gutter has been developed and marketed to complement the plastic cup. The plastic system eliminates contamination from iron cups and gutters which have

reduced gum grades for 70 years. Sulfuric acid will not attack the plastic apron-gutters. and the new

system should prove durable for at least 4 years of continuous use.

Keywords: Plastic apron-gutters and cups, contaminants, gum grades. naval stores.

Gum flows from the pine tree clean and pure.

Reduction in grades and loss in value at the market

are caused primarily by contamination from iron

cups, gutters, and aprons which have been used by

the industry to collect gum since about 1910. Iron

cups and gutters deteriorate rapidly when sulfuric

acid is used to stimulate gum flow, and about 99 percent of the timber worked for gum production in the

United States is treated with sulfuric acid. Most of

the contamination can be prevented by collecting

gum with plastic cups and gutters. A satisfactory,

commercially available plastic system is described

here.

Gum producers receive the highest dollar value

for gum that will produce WATERWHITE and

WINDOWGLASS grades of rosin. The presence of

increasing amounts of iron lowers the grade to

NANCY, MARY, and a very dark KATE. Iron

contaminants increase the ash content or rosin, and

only a small amount of iron rust from cups or

gutters will lower the quality by three grades.

Market prices spiral downward with each drop in

grade.

Since 1972, the Gum Naval Stores Production

Unit of the Southeastern Forest Experiment

‘Naval Stores Research Specialist (Retired), Southeastern

Forest Experiment Station, Olustee, Florida.

‘Naval Stores Forester, Georgia Forestry Commision,

Helena. Georgia.

,

Station at Olustee, Florida, has been devoting considerable research to the problem of iron contaminants. A new plastic cup of tough and durable highdensity polyethylene was developed and introduced to the industry in 1977.’ Producers who have

purchased these plastic cups report better grades

and higher prices.

To complement the plastic cup and complete the

improved collection system, studies were initiated in

1977 by the U.S. Forest Service to develop plastic

gutters and aprons. Drawing heavily upon the cooperation and expertise of the Georgia Forestry

Commission, Macon, Georgia, the experiments of

the two agencies led to the design described and

illustrated here.

ONE-PIECE PLASTIC APRONGUTTER

The new unit is made of polyethylene plastic and

functions as both apron and gutter, balancing the

cup and channeling the gum into the cup. The

apron-gutter is designed to fit trees as small as 9

inches d.b.h., and face widths up to 12 inches can be

‘Clements. Ralph W. 1977. New plastic cup for the gum naval

stores industry. USDA For. Serv. Res. Note SE-25X.4 p. Southeast. For. Exp. Stn., Asheville. N.C.

Southeastern Forest Exyerittwnt Stution - Asheuille, North Carolina
obtained. The outer ends of the one-piece unit contain a cap that provides rigidity to the outer lips and

prevents gum from backing off the ends as waste.

Sulfuric acid, in paste or solution, will not corrode or damage the polyethylene unit. The plastic is

relatively tough, and with normal use and abuse in

the woods the new gutter should have a lifespan of

at least 4 years.

INSTALLATION AND USE

A notch in the outer lip of the apron section enables the gutter to be flexed to fit any tree 9 inches or

larger in diameter. Normally, five double-headed

nails will attach the gutter firmly to the tree if the

bark has been properly smoothed and prepared.

Correct positioning of the nails and installation are

shown in figures 1 and 2.

Figure 2.-The plastic cup should fit snugly under the apron

section to prevent tilting when filled with gum. ,lf the bark

has been properly removed and prepared, a 30-penny nail will

hold the cup under the apron-gutter.

Figure 1 .-The plastic, one-piece apron-gutter installed on a tree

16 inches in diameter. Drive the center nail first, then the

two nails in each wing. If needed to obtain a tight and

leakproof fit on irregularly shaped trees, use additional nails.

On some trees with flat and irregular surfaces, a

tight and leakproof fit can be obtained by slightly

twisting the outer ends of the gutter toward the tree

before nailing on the shoulders. The versatile aprongutter can be shaped to fit tightly on almost any

cylindrical surface because the plastic is flexible,

even in cold weather.

The new plastic cup and apron-gutter system

can be elevated like the standard iron system. However, double-headed nails can be driven completely

through the plastic material by heavy-handed and

careless workers.

AVAILABILITY

The new plastic apron-gutter presented herein is

commercially available, and some 36,000 molded

gutters were installed in 1980 by selected gum producers in Mississippi, Alabama, Georgia, and

Florida. Their reports will help evaluate performance and durability of the plastic units. The onepiece apron-gutter costs a few cents more than the

comparable metal system, but the plastic will enable

the producer to receive top grades and higher

market prices for the life of the system.

Gum producers will find that the new plastic

gutters are tough, easy to install, and acid resistant.

With reasonable care, the plastic apron-gutter

should last longer than the two-piece iron system.

Most important, there will be no iron contaminants in the gum from the collection system to

lower grades.