Glues for Piano Technicians

GLUE

Making the best of a sticky situationDuane McGuire – PTG presentation 11/20/14

We Gather here to talk about GLUE!

Presentation Outline

● Glue Properties● Glue Chemistry● Classes of Glues● Destructive Testing● Details by Class● Demonstrations● Other applications in piano work

General Resources

● Fine Woodworking - A working Guide to Glues● Chemistry Explained – Adhesives● Wikipedia: List of Glues● “Hide Glue”, the book by Stephen A Shepherd

Web Resources for Modern Glues

● Lee Valley Polyurethane Adhesive Guide● Popular Woodworking - The Truth about Polyurethane Glue● Wikipedia: Polyvinyl acetate (PVA)● Wikipedia: Cyanoacrylate (CA)● Hot Stuff CA glue guide

Web Resources for Hide Glue

● Vince Mrykalo - Hot Hide Glue● Facts About Hot Hide Glue from a player piano guy● Lee Valley - Using Hide Glue● Lee Valley - Hide Glue Technical

Glue Properties

Strength Clamp Time Workability

Tackiness Cure Time Gap filling capability

Shelf Life Creep Toxicity

Pot Life Reversibility Water content

Open Time Stain-ability Heat resistance

Longevity Handling Cleanup

Cost Health & Safety

Why does glue stick?

Dude, it's chemistry.

Glue Chemistry 101

Why Does Glue Stick?

Tiny molecules band together to form big stringy molecules called polymers. Polymers stick stuff via:

● Mechanical Adhesion ● Chemical Adhesion● Electrostatic Adhesion

(It's a miracle)

Classes of Glues

Natural● Hot Hide● Cold Hide● Fish● Casein

Synthetic● PVA● PVC-e● Urea Resin● Epoxy● Polyurethane● Contact Cement● Cyanoacrylate

Destructive Testing aka Empirical Analysis

(Boys and girls know how to have fun)

PVA Glues

Polyvinyl Acetate

More PVA

● Bolduc Acoustic Wood Glue

Mentioned in literature:● Franklin Titebond 50● Franklin Assembly 65

(But apparently only

available in large

quantities)

PVA Characteristics

● Relatively safe● Relatively inexpensive● Generally flexible (has some creep)● Long shelf life – except the expensive stuff● First choice for permanent wood joints that are not

reversible● Poor heat resistance. Gums up when sanding.● Polymerizes as water content evaporates

More PVA Characteristics

● Open assembly time 5-30 minutes● Clamp time 20 – 90 minutes● Water cleanup● Reversible with heat for several days● Reversible with water for 2 to 6 weeks

PVA Bolduc

● High solids content● Low creep● Sands well● Recommended and tested by Bolduc for

soundboard, rib, and pinblock applications

What is this stuff?

Franklin Molding & Trim

● No run. No drip.● Hammer hanging● Bridle straps● Hammer spring loops

Epoxy

• Fussy to mix• Long set time• Good gap filler• Resistant to water• Low heat resistance• West System epoxy builds in

success• Toxic• Long shelf life

Urea Resin

• Rigid, creep resistant• Two Part System

(liquid resin, powdered catalyst)

• Short shelf life• Cures hard• Dulls tools quickly• Sands well• Good heat resistance• Toxic!

Polyurethane

• Open time 10 to 40 minutes• Clamp time 45 minutes to 10 hours• Cured glue pares, scrapes or machines

well• Clean up with alcohol or acetone• Fills gaps, but does it weakly• Contains di-isocyanate comounds

which may acutely irritate skin and repiratory tract.

PVC-E

● Polyvinyl Cloride Emulsion● Available from Pianotek Supply (and

Carl Teel)● Formulated for gluing new keytops● Works well with cloth● Cleans up with water● Dries in 10-30 minutes● Residue rubs off nicely for many

hours● Is Aileen's Tacky Craft glue a

substitute? It seems to have similar properties

Cyanoacrylate (CA)

Cyanoacrylate (CA)

● Zero water content● Sets in 30 seconds to 5 minutes● May be accelerated● Cures by exothermic reaction (it gets hot!)● Brittle● Bonds skin (Acetone is a de-bonder)● Fumes are noxious● Glue squirted in eyes causes permanent vision

damage!

Natural Glues

Hot Hide Glue

● Easier to use than you think● Difficult to use for field work● Cures by phase shift (think solder)● Completely reversible forever● May be repaired by re-constituting● Liquifies at 140 degrees Farenheit● Viscosity may be adjusted by user● Strength is reduced each time the

phase is changed● Quick set time – seconds to minutes● Set time may be increased by

warming the room and/or material● Non-toxic

Glue Pot for Small Batches

Glue Pot Options

Cold Hide and Fish Glues

● Properties similar to hot hide glue● Lower strength● Shelf life of 1 year +/-● Fish glue has higher initial tack than cold hide

glue

Piano Applications

First, let's state the obvious: Hide glue can be used for all applications. Basically nothing else was used until 1940.

● Belly work● Action work● Field work● Felt and Cloth

That's what I've got to say about glue.

Hope it sticks!