IV. Sleeping Bags

Shell Construction | Insulation

The conservation of the body's warmth is the main purpose of the sleeping bag. The physical comfort, a soft place to sleep, is secondary and usually is supplied by some means other than the bag, such as smoothing the ground and digging hip holes, placing pine boughs or moss and grass for a bed, or carrying an air mat­tress.

There is wide latitude in what constitutes an acceptable sleep­ing bag for use in summer when not much heat loss need be ex­pected. For winter and extreme cold this is less true. Then use must be made of every factor in design and materials that con­tribute to the insulating properties of the bag. If this is not done, the outfit resulting from careless design will be too heavy and bulky to be practical, or too cold to be comfortable.

Sometimes features of convenience are not compatible with warmth but can be made use of in a summer bag. The summer bag can be rectangular and roomy. It can be made with a zipper down one side and across the bottom allowing the bag to open out into a nice quit for use at home or on cabin beds. This same zipper, if it is of the separating type, can be used with a similar bag to join two single bags into one large one. The top end of the bag may be left completely open for freedom of movement. The tubes holding the insulation can be made by stitching the inside fabric directly to the outside fabric. Each of these is a feature of convenience but detrimental to the overall insulation of a bag to be used at low temperatures. For very low temperatures only bags filled with down with gusseted or diaphragmed compart­ments, running around the bag rather than lengthwise, will be considered.

A bag suitable for below zero temperatures should be form-fitting, tapering at the foot end and fitting close around the body. Heat loss is proportional to the surface area; the smaller the area of the bag the less the heat loss from that source.

SHELL CONSTRUCTION

Zippers are a great convenience, but they are also a fine place to lose heat.  They can be covered with an insulation filled tube, but this contributes to the possibility of snagging the zipper in the fabric, and a snagged zipper can have very serious consequences in extremely cold weather. By the time snagging is guarded against with suitable facings of webbing, a very heavy assembly is the re­sult. Even a bare size 5 zipper weighs one ounce per foot and one long enough to open the bag out completely adds about ½lb. to its weight. No matter what you do with a zipper it is always a stitched through cold seam. The most efficient bags dispense with the zipper entirely.

Velcro Tape is another way to close sleeping bags. In addition to being soft warm fabric, it has the advantage over zippers of closing "in depth" so that instead of a cold stitched through seam, up to 2" of insulation is maintained. Snaps should be set in the center of Velcro Tape about 5" apart to prevent accidental open­ing. If the closure of the bag is made by overlapping the two sides, the Velcro tapes can be sewn only to the layers of fabric that will be in contact (inside the outer flap and outside the inner flap). This must be done before the construction of the compartments and will eliminate cold stitched through seams at the closure. (See Fig. 1, Plate VI.)

For extremely cold temperatures, two single bags that zip to­gether to make a double bag increase the surface area and thus the heat loss beyond what is necessary. The more efficient solution is to make the double bag the actual dimensions of the two people who are to use it. If it is made as snug as is comfortable for two people lying flat on their backs with arms at sides the bag will be less than 2/3 the size of two single bags. It will give a surprising amount of room for various other sleeping positions. If the bag is for very cold weather use, it should fit close and snug around the head to avoid heat loss around the neck. Several methods of doing this are illustrated in Fig. 2, Plate VI.

Other design refinements are necessary as the temperature goes down. Condensed moisture from the breath inside the bag can ruin half its insulating value in a couple of nights. Obviously then it is a good idea to draw the bag close about the neck so that the breath does not go down inside the bag. The head and face pro­tection are thus separate from the body functionally, though not actually detached. This can be done effectively by having a draw­string, preferably with an elastic section in it, just above the shoul­ders. With this arrangement it is possible to have just a square top bag and detachable hood if desired.

Because of the moisture condensation it should also be pointed out that no sleeping bag should be made with a plastic or rubber coated outer fabric. The human body gives up about one pint of moisture during a night and it is essential that this moisture be given an avenue of escape. If the outer layer of the bag is im­permeable and its temperature is below the condensation point all this moisture will condense on its inside surface and soak back into the insulation, eventually destroying its value. Special bags, or some special part of a regular bag, such as the bottom third, can

Be made with an impermeable outer layer provided a similar impermeable layer is used on the inside surface to prevent the body's moisture ever reaching the cold outer layer. In effect this encases the insulation between two water vapor proof layers and keeps it dry and efficient under all conditions. Even with a bag that breathes it is essential to ventilate adequately in use and dry it out frequently because if the bag is insulating properly the outer layer will often be below the dew point and will therefore condense part of the moisture passing through it so that the bag will gradually become damp.

The lining of such a close fitting bag, especially if there is no zipper, should be of a slippery fabric—nylon is the lightest and toughest—making it easy to slip into. True, nylon feels chilly at first but it warms up quickly and the ease of movement it allows makes it well worth the initial chill.

INSULATION

Of course, the biggest contributory factor to the warmth of a sleeping bag is the amount of insulation it gives. Insulation must be had against conductive and convective heat loss for the most part. Radiant heat loss is a very small part of the total.

Conductive heat loss is automatically kept at an inconsequential level by any material of low enough density to act as an efficient convective insulator.

Convective heat loss means the transfer of heat through the movement of the surrounding air. This heat transfer can be caused by the wind, by stirring up of the air mechanically such as the bellows action in the bag when the person turns and tosses, or by setting up of currents due to temperature differences.

Air is the medium of convective heat loss, but is also one of the best insulators against conductive heat loss so that if the possibility of forming convection currents can be eliminated it becomes the ideal insulation. There is considerable drag on the air adjacent to any smooth surface.  Within ⅛" of a smooth surface this drag almost prevents the movement of the air. Outward from this point the air is free to move more and more. By breaking up the air into pockets measuring less than ¼" across its ability to carry heat away by convection can be eliminated.

For the reasons discussed in the Insulation section of the Mate­rials chapter, the greater the thickness of immobilized air the greater the insulation provided. It is the thickness, and only the thickness, that determines the amount of insulation. Whether it is down, kapok, or steel wool that is used to immobilize the air makes very little difference in the actual value of insulation. There are no miracle materials that give more insulation per inch of thickness, as we have said. Thus the selection of an insulating material for the top of a sleeping bag depends on two things. First, it should be the lightest weight possible to fill a given thickness and provide this area with dead air. Second, it should compress into the smallest possible space for packing. To fill these two con­ditions to date nothing better than good waterfowl down has been found. A 50-50 mixture of good quality feathers and down filling the same thickness will be slightly heavier and will not compress quite as much. Dacron batting will be even a little heavier and compress a little less.
The selection of an insulating material for the bottom of the bag, the part one lies on, must have different characteristics, as mentioned earlier. It too should be of the lightest possible weight which will provide the necessary thickness of insulation. How­ever, if this portion of the insulation is as easily compressible as the top of the bag, it will be compressed by the weight of the body and thus lose its thickness—i.e., its insulating value. Therefore, insulation for the bottom of the bag should resist compression as much as possible.

There are various materials which meet these two considera­tions for the bottoms of sleeping bags. Some foam plastics do this very well but are too brittle or non-resilient. U.S. Rubber's En-sol ite, a closed-cell foam, is one of the best insulations for this use but should not be used exclusively since a mattress too bulky to be practical would be the result. The best grade of long staple wool batting, while not giving all the support of the foam plastics, is much easier to incorporate into a practical sleeping bag. The support given by wool can be increased considerably by the addi­tion of a ¼" thick sheet of Ensolite spread on top. This spreads out the pressure over a greater area and compresses the wool even less.  The use of a thin sheet of Ensolite in this manner does not increase the bulk of the bag very much. (See the materials sec­tion for comparisons of these materials.)

The non-compressible materials used to support the body must be used sparingly since they will make a bag too bulky to be back packed conveniently if too much is put in. Insulating only the pressure points of the body results in a bag of convenient back packing size. The points of the body which should be insulated are the hips and shoulders. The feet can be considered a vulner­able point, if not an actual pressure point, due to their extremity and susceptibility to cold. These should be insulated too. The habitual stomach sleeper may wish to consider other pressure points though the shoulder-hip-feet insulation pattern is usually quite comfortable for stomach sleeping. By confining the use of these pads to the pressure points their bulk is kept to a minimum. The areas between these points can be filled with down in the usual manner.

The question of thickness in a sleeping bag depends upon the temperature at which it is to be used and upon the kind of sleep wanted. Strange as it may seem, experiments have shown that it is possible to get a good night's rest even though sleep itself comes only fitfully. If a bag is generally warm but one or two pressure points get cold enough to cause wakefulness, merely turning over and starting again can provide a night's rest that is satisfactory from a recuperative standpoint. Of course, the more the cold spots are reduced the longer the uninterrupted slumber. For a full night's comfortable sleep a much heavier sleeping bag is needed than for a night of recuperative rest. This problem is important only at winter temperatures or at very high altitude.

According to A. C. Burton's Man in a Cold Environment, a sleeping man requires approximately the thickness of insulation shown in the following table for a good night's sleep at various temperatures. This thickness is measured from the skin to the outer surface of the bag, including the air trapped between the various layers of clothing, which can account for up to 1" of the thickness required.

40°	1½² of insulation
20°	2² of insulation
0°	2½² of insulation
20°	3² of insulation
40°	3½² of insulation

We have discussed the insulating materials in a theoretical condition. When they are actually incorporated into a sleeping bag there are many factors that detract from their theoretical per­formance regarding the furnishing of a certain thickness of dead air space. Perhaps the simplest fact to visualize is that the heavier and stiffer the shell fabric used, the more insulating material will be needed to push the fabric out to the desired thickness. Thus, the lightest fabrics consistent with durability should be used, par­ticularly for the top of the bag.

One of the most important and universally overlooked features of good sleeping bag construction is the differential cut. The insulation we are working with is wrapped around a more or less cylindrical object. To anyone familiar with elementary geometry it is obvious that the outer layer of a 2" thick sleeping bag will require about 12½"more fabric to wrap around this cylinder than will the inner layer. Conversely, this means that, when a bag is constructed as a flat quilt and is then wrapped around a body, the outside is stretched and the inside hangs in loose folds. There is nothing to prevent these folds from being pressed out by elbows, knees and shoulders making a thin cold spot in the bag. (See Fig. 3, Plate VI.)

If, on the other hand, the bag is cut to form two cylinders of different radius, and the down compartments made accordingly, it will be almost impossible to push the inner layer out against the outer layer to form a cold spot, as shown in Fig. 4, Plate VI. This is an important consideration because during the course of a night many elbows, knees, shoulders and buttocks will be pushed against the inside of the bag. If these points don't get cold from insufficient insulation it means a much longer period of un­interrupted sleep.
Table of Differential Cuts – In Inches

If bag thickness is	½	1	1½	2	2½	3
Cut the outer circumference this much larger than the inner	3⅛	6¼	9¾	12½	15½	19

An efficient bag should be made to the dimensions of the person or persons using it. These dimensions will differ considerably even though two people may be of the same measurements. Each may want widely varying size bags due to different sleeping habits. The person using the bag should determine his space requirements—is he a thrasher or a quiet sleeper, does he need knee or shoulder space or will he be comfortable in a tighter form-fitting bag? This is the space that should be measured when the size of the bag is being determined. A piece of string should be passed around the body lengthwise, going the maximum distance around the feet. The string should then be pulled as loose as desired for the inside fabric of the bag. This will give the total length which must be designed into the inside layer of the bag. The same tech­nique is used to get the proper circumference around the shoulders and hips.

Another problem in the fabrication of a low temperature sleep­ing bag is the quilting, or forming of compartments to contain the down. Obviously stitching the outer and inner layers of fabric together not only puts holes in the fabric through which warm air can pass, but reduces the thickness to almost nothing, thus elim­inating the insulation at the stitching.

In making a bag using dacron batts it is difficult to avoid the stitch-through construction. However, since dacron is more suit­able for summer bags at medium temperatures anyway, a sandwich of dacron batting between two layers of nylon works out very well. A differential cut allowing for about one inch thickness should be used for a 2 pound batt. If a slightly warmer dacron bag is desired, stitching through all layers can be avoided by mak­ing two separately quilted layers, one a sandwich of the outer layer of fabric and a layer of cheesecloth and another sandwich of the inner layer of fabric and a layer of cheesecloth. The quilting stitching on the inner layer should be offset from that of the outer. To prevent too much interaction or rubbing between the layers a couple of gussets can be sewn into adjacent seams when quilting and eventually sewn together before completion of the bag. (See Fig. 5, Plate VI.) In lengthwise quilting the differential is accom­modated by spacing the quilting lines farther apart on the outer fabric than on the inner.
It is generally a good idea to use down for bags other than sum­mer weight as sufficient thickness of dacron adds quite a lot of weight and bulk.

Down, or down and feathers, are handled quite differently from dacron or other batting. The tubes or compartments are formed first and then the insulation is carefully measured out and blown or placed by hand in each compartment. Here again the problem is to maintain the desired thickness of insulation. The efficiency of down as insulation is largely wasted if the stitched through construction is used, as discussed above. There isn't even the thickness of the compressed batt at the stitching, as with dacron, only the two layers of light fabric are left at the seams. Even worse, the down tends to be held away from these seams for an inch or so on each side.

There are two common methods of avoiding this undesirable stitched through construction. One is the cutting of strips of fabric as wide as the bag is to be thick, plus allowance for seams on each edge. These strips or gussets are then sewn one edge to the outer fabric and one edge to the inner fabric forming box tubes to hold the down. The second method is the use of a third layer of fabric, or diaphragm, which can be nylon netting or some such light material. The use of nylon netting will avoid the dis­appointment of having the inside of the bag come apart long be­fore the rest of the bag is worn out. Nettings are good too because the down tends to get stuck in them and retards shifting. This third layer of fabric is sewn alternately to first the inner then the outer layer of fabric forming triangular sectioned, overlapping tubes. One advantage of this method of diaphragm construction using overlapping tubes is that the natural tendency of the down to pull away from all such partitions, a face which is actually visible in a gusseted bag, is offset by the fact that the thin spot on one tube is under the thickest part of another. It has been demon­strated also that the diaphragm construction gives the greatest thickness for the least weight of down. (See Fig. 6, Plate VI.)

If for some reason, lengthwise tubes must be used in a sleeping bag, the gusseted construction should be used because the dia­phragm construction does not allow the differential cut to shift to a pushed out spot when needed. Where possible, tubes running around the bag should be used and here the more efficient dia­phragm construction may be used.

To accommodate the differential cut in tubes running around the bag the diaphragm must be cut the length of the outer fabric of the bag and gathered as it is sewn to the inner fabric so it comes out even with the smaller circumference of the inner fabric. It is a good idea to key mark center and quarters of the three layers to make sure the gathering is evenly spaced around the bag.
The desired thickness of the bag is governed more by the spac­ing of the diaphragm or gusset seams (width of tube) than any­thing else. These tables are the result of extensive research on experimental compartments filled with the least amount of down.

Once the thickness of the bag is determined and the shell constructed to these dimensions, consideration must be given to the amount of down required to fill the compartments to this thick­ness. A good grade of goose down will fill about 500 cubic inches per ounce. The best trial and error method for determining the correct amount of down is to fill one compartment with a measured amount of down and add or take out small measured amounts until the down loosely fills the compartment. The compartment is properly filled when the down will not settle away from the top when the bag is shaken. Overstuffing a bag with down adds nothing but more weight and bulk. It is the thickness that counts.

The Resulting Thickness Using Minimum Amounts of Down,
for 3 Constructors
compiled by Gerry

GUSSETS 1² wide
spacing of gussets (W)	3²	4²	5²	6²	7²	8²
resulting average thickness	1.75²	1.95²	2.20²	2.55²	2.95²	3.45²

DIAPHRAGM designed 0² thick
spacing of seams (W)	3²	4²	5²	6²	7²	8²
resulting average thickness	.4²	.85²	1.3²	1.7²	2.15²	2.6²

DIAPHRAGM designed 1² thick
spacing of seams (W)		4²	6²	8²	10²	12²
resulting average thickness		1.65²	2.5²	3.35²	4.2²	5²

Once there is enough down to maintain desired thickness—STOP!

The bottom of a bag should never be overstuffed with down. It will take three times more down than wool or other suitable material, by weight, to make the bottom of the sleeping bag warm. This is due to the compressibility of the down. It will not support the body's weight and thin cold spots will result.

The amount of padding used in the bottom of a sleeping bag is limited by the desired size of the rolled bag—usually small. The padding used for support is of course non-compressible and too much will make a bulky bag. As much as is compatible with the rolled size of the bag should be used. Any amount under shoulders, hips and feet will be an advantage for comfort and in­sulation.

In making a bag with a padded bottom it is convenient to en­case the entire bottom in a coated waterproof fabric. A single coated fabric (one side only coated) should be used with the fabric side out (next to the sleeper) and the coated side in (next to the insulation). The entire bottom of the sleeping bag, inner and outer layers, should be encased with coated fabric. This keeps both body moisture, one pint per night, and outside mois­ture from entering the insulation of the padded bottom. It is even possible to avoid stitching through the outer layer of the bot­tom at all by using a layer of nylon netting inside to form com­partments for the padding. (See Fig. 7, Plate VI.) An air escape hole must be put in the inner fabric or it will be impossible to roll the bag up due to the trapped air in the mattress. If a vapor barrier mattress such as this is used, the top two-thirds of the bag must be of permeable fabric.

An excellent and versatile combination is an all down filled sleeping bag of light weight, which is good by itself in summer, and a nylon cover shell incorporating the insulating mattress pads described for winter use. The head can be a compartment to hold extra clothes to form a pillow. Below the pads, pants or other heavy clothing can be used inside the cover shell to extend the in­sulation. If the shell has a coated fabric bottom it makes a dry safe place to keep clothes during the night without actually taking them into the sleeping bag. (See Fig. 8, Plate VI.) This item can be used with a down jacket and waist length down bag for sleep­ing at temperatures down to zero at least.

The trickiest part of making a down filled item is the handling of the down.
Down Blowing

In filling a sleeping bag or down filled garment, the first con­sideration is to divide the down between the various tubes or com­partments by WEIGHT. As little as one ounce will fill 500 cubic inches and yet six ounces can be easily compressed into the same space, so obviously it is practically impossible to guess at equal amounts of down by volume or feel. Scales accurate to ¼ oz. is desirable. If the tubes are uniform as to cross section the down can be apportioned according to length only. If they are not uni­form some rule of thumb adjustments are necessary. To be safe you can hold back a small bit of down for adjustment in case some of the tubes come out short. The scales should be fitted with a one cubic foot open box of heavy paper and the weight of the box sub­tracted at each weighing. The proper amount is the minimum quantity which will not settle down when the tubes are held ver­tically and shaken.

The down can be put in the weighing box by handfuls, grab­bing each handful in the down, compressing it and tucking in all the loose pieces before transferring it to the scales. If the move­ments are slow the mess stays localized. A vacuum cleaner can be used to pick the down out of the weighing box and blow it into the tubes. The tube must be well secured around the exhaust of the vacuum before turning it on. As tubes are filled, roll the ends shut and pin. The down can also be placed by hand, using the same method as used for weighing. In tact it is easier and safer to do small compartments by hand.

A small amount of good down can be used to upgrade a cheap mixture or rehabilitate an old bag. However, it should be dry cleaned first. Dirt is the worst enemy of down and it never pays to mix clean with dirty. After having an old bag cleaned, you may find the down in better shape than the shell. Before trans­ferring old down to a new shell, mix all of the down together in a bathtub or large box, letting dirt and broken filaments settle to the bottom. Mix in a little new down if necessary and proceed as above.

Sleeping Bag

List of Materials

Single Dacron Batt
Fabric—6½ yards 39" or 6 yards 42"
Dacron—one 1 lb. batt
Nylon lace—4 yards
Leather grommet—1
Velcro Tape—42" and 8 Dot Snappers; or one 42" zipper
Double Dacron Batt
Fabric—6½ yards 39" or 6 yards 42"
Cheesecloth—6 yards 36"
Dacron—two 1 lb. batts
Nylon lace—4 yards
Leather grommet—1
Velcro Tape—42" and 8 Dot Snappers; or one 42" zipper
Down Filled
Fabric—6½ yards 39" or 6 yards 42"
Nylon Mosquito Netting—4 yards 44"
Down—1 pound
Nylon lace—4 yards
Leather grommet—1
Velcro Tape—42" and 8 Dot Snappers; or one 42" zipper

Instructions

I.  Read "Layout and Sewing" to familiarize yourself with the terms and operations used.

II. Lay out pieces

(a) Alterations: this bag will fit 75% of the male population but it is best to check the size before starting to cut. Pin a sheet to the inner bag size and crawl in. To make the circumference larger simply add the required inches to both inner and outer diagrams. For the curve of the hood add ¼ of the increase to each station. To change the length either longer or shorter, leave the tube spacing the same and cut off or lengthen the foot end. However, keep the width of the foot as indicated. If this makes the taper appear too abrupt or too long, move the point of taper half as much as the length was changed. If the bag is lengthened more than 3", add another tube. If a tapered foot is not wanted, the foot end can be made rectangular without difficulty.  The opening is made at the side so it can be left open for ventilation while the bag still covers the occupant. If zip-together, matching bags are desired they must be mirror images of one another. If it is desired to make the easiest bag possible, the single batt bag may be cut the same width outside as inside. This saves a good deal of trouble in sewing the quilting.
(b) Cut fabric as long as the bag is wide and piece to length crosswise of the bag, starting at the foot end. Usually only two full widths of fabric are needed to make the length and the hood flap can be pieced on from scraps. The inner and outer tapered pieces may be cut next to each other to prevent waste. Use a hem seam to join the pieces. Make one outer blank and one inner blank being sure that when they are placed together the rough sides of the piecing seams lie between the two blanks.

(c) In marking out the curves make them as smooth as possible but they are not critical as long as the points indicated are accurate.

(d) Mark the quilting or tube lines. For a down filled bag mark on the "between" sides of the inner and outer blanks. The lines are 7" apart. For a 2 batt dacron bag, mark on the outsides of the inner and outer blanks, using every other line from the outer dia­gram or just twice the spacing as for a down bag.   For a single batt dacron bag, use the same spacing on the inner blank as indi­cated for the dacron outer blank. Use chalk to mark outside of bag so it will brush off eventually. For all types of bag, mark a center line where it crosses each tube mark and the head and foot edges.

(e) Cut the blanks to size and shape allowing about ½" for seams.

III. Install insulation

(a) Single Dacron Batt

1. Spread out the outer blank on a clean bare floor (not a rug) or table, marked side down. Unfold a 1 lb. dacron batt on top of this and pull out till it covers all of the blank. Trim edges of the batt until it matches the blank.  Use the scraps to pad out the hip, shoulder and foot areas (in that order of importance).

2. Place the inner blank on top of this sandwich and centered
sidewise between the edges of the wider outer blank. Pin through all three layers at the center marks of each tube line.   Ease half the surplus of the outer blank and the batting toward the center pins and pin again at the quarters of each tube line. Then pin the ends of each tube line so inner and outer and batt all come out even.
3. Sew along the tube lines with the longest possible stitch and loosest possible tensions. Ease the surplus outer and batting into the seam so it is all gone by the time each pin is reached. Remove pins as they are reached. The technique for getting all layers through the machine is to smooth the layers and pull firmly with one hand as the bag goes through the machine.

(b) Double Dacron Batts

1. Proceed as for step no. 1 under Single Dacron Batt, using one of the batts. However, two batts are quite bulky so go easy on the padding with scraps.

2. Proceed as for step no. 1 but using the inner blank and the
other batt. Don't do any padding. In fact, to reduce bulk this batt can be stopped at the bottom of the S curve of the top edge.

3. Cover each blank and batt combination with a layer of cheese­ cloth. Trim cloth to shape and if it doesn't reach full width, don't worry. Pin along the tube marks, using safety pins. If it can be managed, stitch along the tube lines with the fabric side up and the cheesecloth down. Otherwise just sew on top of the cheese­ cloth being very careful that the presser foot doesn't get caught in the cheesecloth and batting. Use the longest stitch possible and loosest tensions.

4. To prevent too much interaction between the inner and outer
quilt, sew a couple of anchor strips in the center tube seams.
Strips of any light fabric 2" wide will do. Sew 2 by their centers in one seam of the outer quilt and sew 4 by their ends in the ad­jacent seams of the inner quilt spaced to match. These will be joined later. See cross section of the Double Dacron Batt bag.

(c) Down Filled

1. Piece together and cut a blank of nylon mosquito netting the
same shape as the outer blank and mark both outer and inner tube lines on it, including center marks.
2. Sew this netting diaphragm alternately to the lines on the inner and outer blanks. In sewing it to the inner blank, the netting must be tucked at frequent intervals so the center marks, and eventually the ends of both pieces come out even.

3. Starting on the edge of the bag, 4" short of the last tube seam, sew across the top edge with a single stitch about ¼" in, tucking the outer, so center and end marks come out even with the inner. Continue sewing down the pointed side and across the foot but using a finished hem seam. The outer must be tucked across the foot to come out even.

4. Fill the tubes with down. Place one fistful way down in each
tube, withdrawing the hand slowly. Repeat with a second and third handful, etc., until all tubes have the same number of handfuls in proportion to their length. For example, 6 each in the longest tapering to 3 in the shortest. Clothespins to close each tube as the down is inserted will help keep the mess under control. When almost all the down is used up, pin each tube closed and fluff up the bag to distribute the down. Hold the bag up so the tubes are vertical with  a  very strong light behind it. Shake until it can be seen that the down has settled in some of the tubes. Place additional down in these tubes, fluff up and shake again. Repeat this until all tubes are filled the same, and the down is all
used up. Be sure to fluff up each time. The tubes up in the hood may be half filled to save down. By weight, the down figures about 11/16 oz. in the longest tubes to ⅜ oz. at the foot, and about ¼oz. in the hood flap tubes.

5. Now close this side of the bag with a finished hem seam.

IV. Finish details

(a) To finish the single batt dacron bag, sew across the head with
a single stitched plain seam, tucking the outer to come out even. Sew down one side, across the foot, tucking the outer fabric, and up the other side with a finished hem seam.  For the double batt bag, place both quilts together, cheesecloth to cheesecloth and sew the anchor strips together so the quilts are held in position. Now sew around the edges just as in the single batt bag. The down bag is already finished to this point.

(b) Cut and piece a facing type of drawhem for the top edge of
the bag and in its center sew a leather grommet for the drawstrings to come out. Install across the top of the bag with the drawstrings securely anchored at the ends.
(c) The bag may be closed with either a zipper or Velcro tape.
In either case, an overlap is used and this is carried down to the foot of the bag with a double row of stitching below the Velcro or zipper.

Velcro tape—set matching snaps about 6" apart in the two lengths of tape and then sew the tapes to the facing surfaces of the bag. Sew the hook tape to the outside of the edge of the bottom of the bag and sew the loop tape to the inside edge of the top of the bag. Be sure the snaps all match up perfectly. Sew both edges of the tape. To close, simply snap the snaps and the tape will stick to­gether by itself. See Fig. 1.

Zippers—sew one half to the inside of the top so the teeth extend past the bag fabric. Sew the other side to the outside of the bottom about 1½" in so a flap will extend over the zipper teeth on the inside. It is a good idea to include a tape between the zipper and the bag to help avoid snagging.

In both cases continue the overlap of the bag down past the closure to the foot and stitch twice about ½"apart. (d) To close the foot, turn the bag inside out. Fold end closed vertically and stitch just inside the edge. About 2" from each end include the center of a couple of tie tapes 36" long so their ends will be outside the bag when it is right side out and so that two little loops will be inside the bag. These are handy to tie down a liner sheet if one is used. If it is desired to stitch out this cold seam across the foot of the bag, pinch up the fabric about 1" back from the first row of stitching and pull out together. Barely catch these folds in another row of stitching as shown in Fig. 3. This row of stitching can also be carried up the side to meet the closure but will use up 2" of the inside circumference.

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