SSIA Bonding Class Video

video on adhesives by Jim McFarland for SSIA

Notes

Tips

• fume extraction
  • even just a fan
• contact cements
• other cements for modern materials
• Barge Infinity line for synthetics, especially sneakers
• basic contact cements
  • all purpose
  • leather, rubber, EVA 80% of the time
  • drying times vary
• never force dry
  • no more than just laying in fume extractor, use air conditioning
  • no heat lamp or no heat gun unless reactivating dry cement
  • will dry on top, but leave wet layer beneath, leading to separation, especially on rubber
• green strength
  • analogy to Velcro
  • doesn’t work until it’s completely dry
  • waste of time to put together wet
  • takes 30–40 minutes for green strength to kick in
  • sanding on wheel creates heat, leading to separation
  • continues getting stronger for a day or so
  • let dry overnight before sanding
  • give at least 45 minutes
• super glue
  • thick and thin, your preference
  • many good uses, many bad uses
  • bad: straight on leather
    • brittle
    • nightmare to repair
  • bonds many synthetics, but not polyethylene
  • repairing men’s shoe heel pulled off:
    • rough leather
    • put contact cement on leather, let dry 30–45 minutes
    • put bead of super glue around rubber or plastic heel
    • use press, preferably right side up, to avoid super glue running down
    • super glue will stick to rubber in the adhesive
  • don’t use super glue as a primer5%
  • burning in eyes, nose, throat
    • glue activated by moisture
    • fumes hitting moist areas
    • avoid with ventilation
    • avoid using so much
• thinners
  • each brand has own thinner
  • designed for the products
  • recommends using matched thinners
• use different glue pots for different adhesives
  • e.g. Colle de Cologne will curdle like milk when mixed with others, even when there’s just a drop in a pot or a brush
• 2 quarts often the price of a gallon
• in industry, normal to use a gallon a week or more when busy
• lots of sneaker people use Barge Infinity
• Top-Fit can be used on wet leather
  • e.g. cased leather for cowboy boots
  • can help stitching to open up the leather
• most cements don’t need two coats
• thinner
  • doesn’t recommend diluting a lot with thinners
  • only pour out enough cement that you’ll need for the day or the week
  • solvents from new cement added will loosen dried cement in the pot
  • only adds thinner to pot when cleaning out
  • uses thinner to break down shoes
• Renia blue-label hardener
  • e.g. for people working in hot places, like restaurant workers or roofers
  • 5% mixture
  • mix in a separate container, not your glue pot
  • takes effect in about 24 hours
  • prevents things penetrating the adhesive

Demos

High Heel Top Lifts

• tip from Robert DiRinaldo
• made the presses Jim uses [They look like big c-clamps with enlarged pads on the screws and thick metal bases.]
• can’t nail into soft, spongy materials
• auto-soler wire is expensive!
• looks better without nails in bottom of heel
• bead of super glue around the heel body
• spread around with the top lift
• sand the back of the top lift strip every time
• put in press for a minute or two, topside up
• can use some hydraulic presses
• no scratching floors with nail heads
• heavy shears to trim away excess around the heel

Material Identification

• easy to tell rubber
• easy to tell leather
• easy to recognize crepe/EVA
• tricky: EVA from polyurethane
  • look similar
  • especially if sanded
  • polyurethane usually a one-piece, molded-on unit sole
  • polyurethane is open cell
    • it rots, crumbles
    • has a “shelf life”
  • EVA doesn’t
  • Red Wings: usually pretty dense PU, get ten years or so
  • EVA wears quicker
  • open cell absorbs water and humidity
  • not oil resisting once bottom worn off
  • EVA repels liquids a bit more
  • stretching fluid soaks right into PU
  • bonding EVA easy with contact cements
  • bonding PU with contact cement hard, or more complicated

Repairing PU Outsole

• some avoid bonding problems by rewelting, adding a midsole, but that’s a lot of work
• vinyl cements
• approach: sand down, leaving the thickness of a midsole, not all the way down
• did many Red Wing Super Soles, years ago
• method 1
  • Renia Syntic Total
  • Barge Vinyl Stick
  • Barge Infinity
  • Master Vinyl Cement
  • dries quickly
  • not a contact cement
  • then heat activate
  • also coat the replacement sole
  • have open times, but they’re very short, and you can get interrupted
  • heat lamp or heat gun
  • press evenly
  • 30–35 minutes
• method 2: Colle de Cologne with PUR primer
  • green label primer
  • green label: go! no waiting
  • pour out into a mixing cup, not in the container, will get white, powdery crystals
  • generous coat on the new “midsole”
  • CdC on top, right away, while wet
  • now open time of 15–20 minutes
  • demo: Vibram lugged
    • sand to prep
    • yellow Rehagol primer for high-abrasion rubber
    • don’t have to worry about delaminating from heat during sanding
    • Yellow label: slow down or stop
    • pour into separate container
    • don’t reuse dauber from other primer
    • let dry about 10 minutes before cement
    • “chemical roughening”
    • can feel the roughness
    • doesn’t work on EVA
    • could use CdC directly on EVA outsole
    • vinyl cements typically don’t work well on EVA
• some polyurethane soles come with a peel-off cover, pre-primed with vinyl cement, so just have to put contact cement on top

Identifying TPR

• on a lot of shoes
• seeing less than used to
• if you sand the heel down, it’s hollow in the middle
• thinner destroys TPR
• test: thinner on a rag, rub a spot in middle of sole
  • men’s shoe
    • shiny spot
    • color comes off on the rag
    • not just dirt coming off
    • reheeling high abrasion rubber
      • super glue
      • vinyl cement
    • same for thin full sole layers
  • ladies heel
    • positive
    • color came off
    • blew on the spot, became shiny
    • can’t use regular contact cement
    • method 1: vinyl stick cements, PU-based
    • method 2: Rehagol primer and contact cement

Identifying PVC

• don’t see too often
• on sanding, it melts
• chlorine rises to top under heat, becomes goo, drips off, burns skin
• thinner on rag test doesn’t work
• example: Dr. Martens
• Red Wing SuperSole may be lined with a thin layer of PVC around the edge
• use thinner on rag to clean sanded bottom to remove the chlorine, counteract greasiness
• Colle de Cologne
  • one of the few contact cements that works on PVC
  • no primers
  • let dry overnight once stuck together, then trim
• urethane vinyl stick adhesives
  • all work well on PVC
  • let dry 10–15 minutes
  • use heat gun or heat lamp, then press new material on
  • let dry at least 45 minutes, better overnight
  • then trim