Treating Christmas Trees to Reduce Fire Hazard

Treating Christmas Trees to Reduce Fire Hazard

After investigating a number of methods considered to have possibilities for making Christmas trees less flammable, the U. S. Forest Products Laboratory has concluded that keeping the tree standing in water is about the most practical, satisfactory, and convenient method of those tried for reducing the fire hazard and preventing the needles from discoloring or falling. Additional protection against fire can be provided by the use of fire-retardant coatings in conjunction with the water treatment if the retention of the natural color of the foliage is unimportant.

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Recommended Treatment

The procedure recommended for the water treatment is as follows:

  1. Obtain a tree that has been cut as recently as possible.
  2. Cut off the end of the trunk diagonally at least 1 inch above the original cut end. Stand the tree at once in a container of water and keep the water level above the cut surface during the entire time that the tree is in the house. If the tree is not to be set up for several days, it should be kept standing in water meanwhile in a cool place.

If started in time, this treatment not only will prevent the needles from drying out and becoming flammable, but it will also keep them fresh and green. It will, in addition, retard the fall of needles of such species as spruce, which losses needles very easily, in contrast to balsam fir, which retains its needles even after the branches have become dry and the needles brittle. Freshly cut spruce or balsam fir trees standing in water cannot be set on fire by candle or match fires, but, of course, will not withstand a large source of heat.

Decorative Coatings

Several types of fire-retardant coatings that either prevent or greatly retard flame spread when applied to wood will provide similar protection when applied to Christmas trees.

For those willing to undertake the extra trouble and expense in the use of decorative coatings, the following simple formulations are suggested:

This type of coating can be made at home by mixing equal parts of a commercial white lead paint and of a boraxlinseed oil paste. The paste is prepared by stirring together one part by weight of boiled linseed oil and two parts of borax ground and sieved to remove coarse lumps.

In applying any of the foregoing coatings the fact must be kept in mind that a heavy coating is necessary to reduce the fire hazard. Two coats are recommended. The coatings may be applied either by dipping or by spraying.

It may be necessary to thin formula I for spray application in which event more applications arc necessary. Silver effects can be had by spraying an aluminum paint on trees coated with either formula II or III.

If a coating is applied, it is recommended that the water treatment also be used to insure the added protection against fire that the moisture in the tree provides. Furthermore, experiments have shown that the water treatment improves the adherence of brittle coatings, such as formulas I and II, because the moisture-filled needles do not shrink and thus allow brittle coatings to flake off.

Fire-Retardant Chemical Solutions

Experiments at the Forest Products Laboratory have shown that the introduction of several fire-retarding chemicals into spruce resulted in one or more of the following: needle discoloration, needle fall, increased combustibility. The increase in flammability was due to the fact that chemical solutions were taken up by the tree neither so rapidly nor in such large amounts as water, and trees actually lost weight while being treated with chemical solutions. Thus, while the trees were taking up some fire-retardant chemical, they were losing another excellent fire retardant, water.

As a specific example, ammonium sulfate caused serious discoloration of both spruce and balsam fir needles. Spruce needles started to fall 2 days after treatment and by 5 days were falling freely. (Reports that have come to the Forest Products Laboratory from those who have used the ammonium sulfate treatment have revealed similar experiences). Both spruce and balsam fir treated with ammonium sulfate were more flammable than water-treated specimens. The spruce was more flammable than the balsam.

Extra Fire Precautions

In addition to these treatments, all possible precautions against fire should be in effect around the Christmas tree, including the elimination of defective electrical connections, and avoidance of the accumulation of combustible decorations on or beneath the tree; the tree should be placed so that its accidental burning would not ignite curtains or other combustible furnishings nor trap the occupants of a room or building.

Treating Christmas Trees to Reduce Fire Hazard

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Treating Christmas Trees to Reduce Fire Hazard

After trying various chemical treatments suggested for making spruce and halsam fir Christmas trees less inflammable, the U. S. Forest Products Laboratory has concluded that keeping the tree standing in water is about the most practical, satisfactory, and convenient method of those tried that will keep the fire hazard low and prevent needles from discoloring or falling. The procedure recommended is as follows:

  1. Buy a tree that has been cut as recently as possible.
  2. Cut off the end of the trunk diagonally at least 1 inch above the original cut end. Stand the tree at once in a containey of water and keep the water level above the cut surface during the entire time that the tree is in the house. If the tree is not to be set up for several days, it should be kept standing in water meanwhile in a cool place.

If started in time, this treatment not only prevents the needles from drying out and becoming inflammable, hut it will also keep them f.resh and green and retard the fall of needles of such species as spruce, which loses needles very easily in contrast to balsam fir which retains its needles even after the branches have become dry and the needles brittle. Freshly cut spruce or balsam fir trees standing in water cannot be set on fire by candle or match fires, but, of course, cannot withstand a large source of heat.

Regardless of treatment, all possible precautions against fire should be in effect around the Christmas tree, including the elimination of defective electrical connections, and avoidance of the accumulation of combustible decorations on or beneath the tree; the tree should be placed so that its accidental burning would not ignite curtains or other combustible furnishings nor trap the occupants of a room or building.

The above observations on water vs. chemical treatment of Christmas trees were made during tests in which spruce and balsam fir branches were allowed to take up water and solutions of ammonium sulfate, ammonium phosphate, ammonium sulfamate, and calcium chloride. It is probable that the effect of a water treatment on other species would he similar to the effect on spruce and balsam fir, but other species may or may not react similiarly to treatment with chemical solutions.

With respect to the chemical treatments tested, a general observation, which may be applicable in the case of other chemical treatments, may be pertinent. It was observed that the chemical solutions were neither taken up so rapidly nor in such large amounts as was water, and the trees lost weight while being treated. In other words, while they were taking up fire-retardant chemical they were losing another excellent fire retardant, water. In general, the more concentrated the chemical solution, the less the rate of absorption.

A summary of results of treatments of spruce and balsam fir with solutions of various concentrations of ammonium sulfate, ammonium phosphate (both mono-and diammonium phosphates and a mixture of both), calcium chloride, and ammonium sulfamate is as follows:

Ammonium sulfate.—Caused serious discoloration of both spruce and halsam fir needles. Needles started to fall 2 days after treatment and by 4 or 5 days were falling freely. Treated spruce specimens decidedly more inflammable than watertreated specimens. Balsam fir specimens not so inflammable as the spruce, but not significantly less inflammable than water-treated specimens.

Ammonium phosphates.—Results similar to those obtained with ammonium sulfate.

Calcium chloride.—Needle color and fall not seriously affected. Fire resistance of specimens treated with 40 percent solution less than that of water-treated material. Fire resistance of material treated with 20 percent solution comparable but not superior to water-treated.

Ammonium sulfamate.—Caused needle discoloration, but no needle fall although needles became brittle and were easily loosened by handling. Fire resistance of material treated with 40 percent solution approximately equal to watertreated controls. Considerable fire retardance after specimens were allowed to dry.

Although these experiments with materials of known fire .retarding possibilities failed to disclose a chemical treating material superior to water, they do not prove that such treatment is impossible. Until some other treatment for spruce and balsam fir is proven to be substantially superior, water, if used under the conditions specified, will serve well at little cost.—Forest Products Laboratory, U. S. Forest Service.