Medical Face Shields, as built by Sailworks

April 6, 2020

Recognizing the shortage of PPE gear for healthcare workers in our community at this time of virus crisis, we set about to make face shields (a.k.a. "visors") using materials we had on hand in our windsurfing sail loft. This face shield design evolved through eight prototype iterations and was tested by local physicians, nurses, clinicians, hospital infection control managers, hospital materials managers, and the local public health officials. These face shields are lightweight, just 1.1 oz., easy to put on and adjust, secure and comfortable to wear. In the past two weeks, we made 6,800 face shields using the materials and methods described below.

Medical Face Shields by Sailworks Covid 19

This isn't the only way to make a PPE face shield, but this method and construction is a fast and cost-effective way to mass-produce a face shield that is wanted and appreciated by healthcare workers and first responders.

 

Link to Surfer Today article "Sailworks shifts production to medical face shields" from March 27th, 2020. 

 

Materials

The clear shield lens is 7-mil monofilm (0.007" PET film) that is commonly used for window panels in windsurfing sails. The lens is 13" wide by 9" tall, with 3" radiuses to the lower corners. See the attached DXF file.

The lens has a forehead stand-off made of foam, 1.125 " square in end profile, by 13" long. The foam is open-cell polyurethane, PU-2540 (2.5 lb density, 40 ILD). We purposely chose this foam as it has the best bonding characteristics to the two-sided PSA seam tape. The 2540 foam is soft and has a slightly sticky feel to touch. It fully bonds to the seam tape, such that when you try to pull the foam away from the tape the foam tears, but the foam/tape bond does not fail. The 1.125" dimension was chosen to allow a slight assembly tolerance to stick the foam in place, and the square profile to ensure the foam strip could be stuck down in any axis to speed up that process.

The double-sided tape we used is a premium sailmaking seam tape with a high adhesion acrylic adhesive and polyester carrier. Its translucent, UV stable and non-yellowing with an excellent initial tack and long term bond.

The elastic chosen is a 1" knitted elastic. Knitted elastic maintains its width when stretched (as opposed to woven elastic, which narrows when stretched), and it has an open structure that is not as hot or compressive to wear as a headband.

The elastic headband uses a 1" tri-glide fastener for easy length adjustment.

Specific materials, part names and sources are listed at the end of this document.

Cutting the Materials

At Sailworks we have an Autometrix single-ply flatbed digital cutting table that we used for cutting the 7-mil PET film. The material is held in place by vacuum as the carriage and cutting head moves along. Our cutting table is 6' wide x 21' long. We can nest 120 pcs of the face shield lens over the table length and cut the entire table in under 7 minutes. The PET film is susceptible to fingerprints and scratches from handling, so we wore nitrile gloves whenever the PET film was handled.

Medical Face Shield cutting materials

The 2540 PU foam was ordered from a regional foam distributor, custom cut in 82" x 13" x 1.125" planks, which we then cut by hand to 1.125" x 1.125" x 13" strips. The narrow width and slightly sticky nature of the foam did not lend itself well to machine cutting. We used Olfa 1" snap-off blade knives with copious blade lubrication with McLube Sail-Kote dry Teflon spray. Without the Teflon spray, the blades would only cut cleanly for 10-15 strips, whereas a frequently lubed blade would cut two planks worth (140+ strips) before losing its edge. We used a steel ruler the same width as our strips (1.125") to cut against and applied 2-sided tape to the top side of the ruler to keep the ruler stuck to our fingers (and our fingers out of the way of the knife) while cutting. We were cutting strips cleanly, and square at 20 strips per minute, then stopping to lube the blades.

Cutting foam for medical face shields

The elastic was cut by foot-pedal hot knife. Cut lengths for the elastic are 8" for the tri-glide side and 12" for the adjustment side, one piece of each per shield.

Assembly

The seam tape was applied to the foam strips first, by pinning the 1" seam tape out, sticky side up, in long runs, and applying the foam to the tape in long chains. We prioritized the bond of the foam to the tape, where we could use a hand roller to firmly press the foam into the tape to ensure a good bond. The taped foam strips were then cut apart to individual pieces.

The shorter 8" piece of elastic requires lacing onto the tri-glide fasteners, then elastic parts were then sewn. One end of the shorter (8") elastic is bar-tacked to the center bar of the tri-glide fastener with as short a tail as possible. One end of the longer (12") elastic is folded and bar-tacked to itself to form a 1/2" stopper end. We ganged up long runs of the parts and bar-tacked them on automatic Juki LU-2828 sewing machines with a 5-stitch x 5 pass stitch pattern.

The free ends of the elastic parts were then pre-taped across the 1" seam tape in long chains, rubbed out with the hand roller and then snipped apart in groups of 20 pcs. The 20-pc groupings aiding in keeping count of parts in progress, and made the tape backing removal fast and manageable (i.e. remove a single 20-pc tape backing and then cut the elastics apart, rather than cut the elastics apart and then remove twenty 1-pc tape backings).

Cutting elastics for medical face shields

The elastics pieces were then stuck onto the upper corners of the PET film lens with a 1" x 1" contact area, with an alignment template positioned below. The seam tape bonding to the PET film is instant and permanent, so placement of the elastic has to be precise at the first drop.

The elastics were then stapled twice within the 1" x 1" contact patch with a pistol grip stapler, with the turned end of the staples to the inside (to be later covered by the foam).

Medical Face Shield

Some background here, as stapling the elastic to the PET film was a hot point of discussion and testing in our development of the face shield construction. It's not a very high tech or elegant solution, but it proved to be the best choice for a few reasons. First, it is fast and easy and imposes the least amount of handling on the PET film lens. It also proved to be quite strong for the purposes of the face shield. The alternatives we tested were sewing the elastic to the PET film, both with bar-tacks and box stitches patterns, neither of which were stronger than the staples. PET film does not like to be sewn directly and requires some additional reinforcing to adequately hold stitches (we're experts in this area from our sailmaking) which would add to the cost and assembly time. Further, we also found that sewing the elastic in place increased the handling of the PET film and the potential for scratching the film.

The pre-taped foam strips are then placed across the top of the face shield. The 2-sided tape bonds readily to the PET film, but extra pressure is applied to the ends of the foam where it is bonding to the elastic ends.

The last step is to lace the adjustment end of the elastic and its bar-tacked fold, through the tri-glide fastener. When set to its longest adjustment length, the face shield will lay flat for easy packing. We were provided a face shield care sheet by the Health Dept (see attached file) that we interleaved between the face shields to help stop scratches during shipment. We packed 10 shields to a 14" x 27" polybag, and then ten 10-packs into a 24" x 14" x 14" box.
 
Good luck with your face shield production! We're sure your local healthcare providers will be grateful.
 
Bruce Peterson
 
 

STOP THE VIRUS!!

 

Materials and Sources We Used

0.007" PET film

      Part name: 7-mil Monofilm 
Dimension-Polyant
78 Highland Drive
Putnam, CT 06260, USA
Contact: Zack Clayton
Direct: 860-928-8327
zack.clayton@dimension-polyant.com
www.dimension-polyant.com

Part name: #E088, 7-mil Monofil
m
Bainbridge International Inc.
15242 Transistor Lane
Huntington Beach, CA. 92649-1142
Contact: Erik Reynolds
Office: (714) 373-3322
EReynolds@bainbridgeintusa.com
www.bainbridgeintusa.com

Part name: Melinex 516, 0.007" PE
T
PolymerFilms
3311 E. Central Ave.
Fresno, Ca 93725
Contact: Yvette Causor
T: 559-383-3456
ycausor@polymershapes.com
www.polymerfilms.com

1" High Tack Seam Tape

Part name: #J446  
Bainbridge International Inc.
15242 Transistor Lane
Huntington Beach, CA. 92649-1142
Contact: Erik Reynolds
Office: (714) 373-3322
EReynolds@bainbridgeintusa.com
www.bainbridgeintusa.com

 

Part name: BT-89538 Clear PET tape or #3869 TESA 
Bron Tapes Northwest
6970 South 220th Street
Kent, WA 98032
Contact: Chris Longphre
c 541-400-0259
crlongphre@brontapes.com
www. brontapes.com

Foam

Product name: PU-2540 
IN-EX UPHOLSTERY SUPPLIES
2234 NE Columbia Blvd
Portland, OR 97211
Contact: David
503-235-0614
supplies@inexupholstery.com
www.inexupholstery.com

Elastic

Product name: EL1BL (black) or EL1WH (white) 1" knit elastic 
Rex Pegg Fabrics, Inc.
Contact: Dustin Snyder
253-272-5162 | 1-800-933-3232

dsnyder@rexpeggfabrics.com
www.rexpeggfabrics.com

 

HiTex Corp 
16110 Woodinville-Redmond Road NE
Woodinville, WA 98072
Contact: Terri Rollins
Tel: (800) 286-0659 terri@hitexcorp.com
www.hitexcorp.com

 

Perfect Fit 
6633 NE 59th Pl
Portland OR 97218
Tel:503-234-9325
sales@perfectfit.com
www.perfectfit.com

Fastener

Part name: 1" tri-glide #105-0100 
Fastening Systems
2288 Valley Boulevard,
Pomona, CA 91768
Contact: Connie Colburn
Tel: 909-464-1263
ccolburn@fasteningsystems.com
www.fasteningsystems.com

 

Downloadable Resources: