Viable Alternatives & Substitutes for P2 in Electroplating and Surface Finishing

Presented By: Frank Altmayer, MSF, AESF Fellow, Technical Education Director, AESF Foundation/NASF Presentation Overview: 1. Alternatives to Electroplating: • Mechanical plating • HVOF thermal spray systems • Physical vapor deposition • Ion Implantation 2. Substitution: • Decorative Cr+3 for Cr+6 • Decorative Sn-Co for Cr+6 • Cr+3 for Cr+6 conversion coatings for Al • Non-cyanide silver for cyanide silver • Non-cyanide copper for cyanide copper • Zn-Ni for Cd HVOF Spray • Cu-Zn-Sn vs. Ni • Citric acid for nitric-chromic passivation of SS • Biologic cleaners for alkaline soak cleaners • Inhibited acids for non-inhibited acids • UV curable maskants Photo by F. Altmayer

Mechanical Plating

Coatings: • Zinc • Cadmium • Tin Metal Flake/Powder Media (Glass Bead) • Aluminum • Copper Coating • Indium

• Lead A Clean Ferrous Surface Forms an Intermetallic Bond With Certain Soft • Combination layers Metals Upon Intimate Contact (Energy is Provided By Media-Glass Beads)

Photo/Illustrations by F. Altmayer Mechanical Plating Advantages: Disadvantages: • No Hydrogen Embrittlement • Worker Exposure to Metallic Dust • Easy Waste Treatment • Limited Number of Substrates • Unusual Metal Combinations • Lower Level of Surface Appearance • No Build-up on Sharp Edges • Limited Part Sizes • Nesting Not a Problem • Controlling Thickness is Hard • More Uniform Coating vs. Galvanize • Recesses, Blind Holes Not Plated • Coats Powder Metallurgy w/o • Media Lodging Problem Impregnation • Limited to Soft Metals for • Common substrates: Coatings - Steel, Copper/alloys, Stainless - Aluminum, Copper, Cadmium, Steel, Powder Metallurgy Indium, Lead, Silver, Tin, Zinc, Combination layers

HVOF Thermal Spray • Powder is heated, at 2500-3100°C, to a plasticized state and is simultaneously propelled onto a surface

• Coating consists of interlocking and bonded layers of thin lenticular particles, called splats, interspersed with voids

• Splats harden rapidly

• Commonly sprayed powders: − W-C-Co − W-C-Ni − WC − Cr-C − Co-Mo-Cr Photo/Illustration by F. Altmayer

HVOF Spray vs. Hard Chromium Coating Features: Considerations: • High Wear Resistance • Development of • Good Corrosion Resistance deposition parameters • Good Adhesion • Appropriate powder • Low Porosity • Part preparation method • High Density • Finishing/sealing • Low Fatigue Impact requirements • No Hydrogen Effects • Difficulty in stripping • Polished To Mirror Finish • High capital investment

• Rapid Coating (minutes vs. hours) • Simpler Masking HVOF Spray Additional Limitations: Surface Preparation: • High Equipment Cost • Degrease • Requires blasting of parts • Blast Finish • Intense UV light • • Dust & Fumes Alumina − Baghouse Required • Silicon carbide • Constant Distance Requirement − Robotics Required • Limited to parts with simple geometries

High Velocity Oxy-fuel Spraying

Metal Powder Mix Mechanism:

Fuel Fuel • Oxygen/fuel gas and powder are introduced into the combustion chamber

O2/Air • Combustion yields hot, high pressure gas

• Powder is heated/accelerated − > 800 m/sec (2600 ft/sec)

• Thin ribbon of coating is produced − Thickness/width changes with each specific HVOF process. − • Positioning of ribbons side by side yields Substrate a smooth/uniform coating

Illustration by F. Altmayer HVOF vs. Hard Chromium Adhesion Bond strength of chrome plate = ~ 9,000 psi Bond strength of HVOF coatings = >>10,000 psi

Wear HVOF coatings (WC-Co) = 4-5 X Better

Corrosion Protection Hard Chrome plate • Good salt spray resistance • Poor crevice corrosion resistance

HVOF Coatings • Good salt spray resistance • Excellent crevice corrosion resistance

Mechanical Properties Hard Chrome plate • Normally tensile stressed MD-80 Slat Track • More prone to cracking/fatigue failure HVOF Sprayed on Roller

HVOF Surfaces • Normally compressive stressed • Less prone to cracking/fatigue failure Photo by F. Altmayer

HVOF Spray Properties vs. Hard Chrome

Fatigue: Hard Chrome: • Lowers fatigue strength (4340 steel)

HVOF Coatings: • Lowers fatigue strength but to a lesser degree than chrome

• At elevated cycles some coatings enhance fatigue strength

Hydraulic Cylinder Leakage: Drops • Significantly lower level of leakage for HVOF vs. Hard Chromium

Cycles Polishing & Stripping HVOF Coatings Polishing: • Must use diamond based abrasives • Requires superfinish to remove debris • Small Level of surface porosity remains Superfinish Polishing Stripping: • Reverse current in Rochelle salt Stripping Process: solution Na2CO3 20-30g/L Rochelle salt 8-12g/L • Resistant to water jet stripping Temperature 104-150°F • Some coatings on some parts (T400 pH 11-12 vanes for example) are nearly Volts 4-6 impossible to chemically strip CD 4-8 ASI • High capacity rectifier required Photo by F. Altmayer Physical Vapor Deposition (PVD) Definition: A group of surface coating technologies used for decorative coating, tool coating, and other substrate coating applications Vapor Phase

Basic PVD Deposition: Solid Phase A vacuum environment process employing atom by atom transfer of Basic PVD material from the solid phase to the vapor phase and back to the solid phase, gradually building a film on the surface Reactive PVD to be coated Gas Reactive PVD Deposition: + Depositing material reacts with a gaseous back-filled into the vacuum chamber to produce a compound coating, such as a nitride, oxide, carbide or carbonitride. Physical Vapor Deposition (PVD)

Advantages: • Compatible with many metals and plastics • Can produce harder coatings than can be applied by electroplating • Can produce alloys that cannot be produced by any other method • Few limits on type of inorganic coatings applied • “Dry” process (eco-friendly) TiN

Photo from Wikipedia Physical Vapor Deposition (PVD) Disadvantages: • Parts may be exposed to high temperatures • Not usually good choices for parts such as fasteners • Line-of-sight processes • May require special training by operating personnel. • Trial & error to determine best PVD technology for given application • High capital costs (near clean room environment required) • Parts typically require electroplated layers TiCN

for maximum corrosion protection Photo from Wikipedia

Ion Plating

• AKA: Ion assisted deposition (IAD), ion vapor deposition (IVD) • Specimens and source material are placed in a vacuum chamber back-filled with an inert (Ar) or reactive gas (NH4, CO) • A low-voltage arc + heat evaporates a portion of the source material

• Coating is formed by bombardment of specimens with accelerated target particles

• Films having good adhesion, fine microstructure, and high density are possible

• Typical thickness = 10 - 30 microns

• Deposition rate = (0.000001-0.000006”/minute Photo and illustration by F. Altmayer Sputter-Ion Plating • Precise Control Over Compositions • Ability to Deposit Thick Multilayers • Variety of Deposited Coatings • Low Thermal Loading • Deposit is Free of “Droplets” • Ability to Automate • Environmentally “Friendly” Ion plated copper on • In-situ Sputter Cleaning molybdenum mirror surface • Better Coverage/Uniformity • Coating Properties Not Related to Incidence Angle of ions • Coating Properties Can Be Manipulated • Better Adhesion • Finer Microstructure • Less Porosity . The deposition rate = 5 - 30 angstroms/sec. • Typical thickness = 10 - 30 microns

Sputter-Ion Plating Computer Controlled: Disadvantages: • Timing • • Gas Pressures Many Variables to Control • Temperatures • Difficulty in Obtaining Uniform Bombardment (line-of-sight) Factors Affecting Color: • Excessive Heating of Substrate • Gas Inclusion in Coating • Mass Density • Substrate Irradiation (X-rays) • Partial pressures of reactive gases • Electroplated under-layers required • Evaporation Rate • Racking is labor intensive • Temperature • Part size is limited • Target material -- Purity • Highly stressed deposits at high • Out gassing of substrate thickness • Contaminants

Sputter-Ion Plating Typical Process Flow: 1. Nickel-Chromium Plate 2. Inspect 3. Rack 4. Clean 5. Dry 6. Load into PVD chamber 7. Pump down 8. Plasma cleaning 9. Deposition 10. Vent chamber 11. Unload 12. Un-rack 13. Inspect 14. Package for shipment Substrates for PVD Substrates Amenable to PVD: Substrate Requirements: • All Steels • Compatible with high vacuums and temperatures. Materials that outgas • Copper Alloys under vacuum conditions or may • Stainless Steels change metallurgically are not suitable • Titanium alloys • Size limitations (must fit in chamber • • Nickel alloys Fixture marks will be produced • Strict cleaning requirements-blasting • Cobalt alloys may be required • Carbide • Surface finish cannot be rougher than • Ferro-tic coating thickness • Assemblies typically cannot be coated • Cermet or are very hard to coat • Aluminum alloys • Welded parts are troublesome. They • Ceramics can be coated if the welds are scale- • Glass & some plastics free and free of pores • Brazed or silver soldered parts must be • Certain high temperature cadmium free (tends to vaporize) plastics • High precision(+/-0.0001”) • Beryllium • parts may experience thermal effects • Nickel/Chrome plated parts Ion Implantation

• In a vacuum chamber (10-5 Torr), ions are accelerated in an electrical field and directed to a target surface Surface Roughening • Ions strike the surface of the target with kinetic Reflected energies 4–5X greater than the binding energy Ions of the atoms in the target Ion Beam • Physical and chemical structure of the surface is altered • Penetration depth is typically about 0.1 micron • Ions implanted include Ag, Al, Ar, As, B, Be, C, Ca, Cl, Co, Cu, F, Fe, Ge, H, He, K, Kr, Li, Mg, Sputtered Atoms Mn, N, Na, Ni, O, P, Re, S, Si, Sb, Ti, V, Y, Zn Implanted Ions • Targets may be made of metals, alloys, semiconductors, ceramics, glass and plastics Ion Implantation

Surface Advantages: Roughening

• Environmentally “friendly” Reflected Ions • Modified surfaces may offer better Ion Beam wear, lower coefficient of friction, and more corrosion resistance vs. hard chromium • Low operating costs ($100-1000/m2) Sputtered Atoms • Substrate subjected to low process Implanted temperature (<150°C) Ions • No Hazardous gases, liquids, effluents

Ion Implantation

Disadvantages: • Capital intensive ($500,000 minimum) Surface • Lots of trial error on dosage and energy Roughening level for best results Reflected Ions • Highly trained personnel required Ion Beam • Crystal structure of the target can be damaged or destroyed • Line of sight process (to 45°) • After service, worn surface may be Sputtered especially difficult to refurbish Atoms Implanted • Electrocution hazard Ions • Radiation hazard • Targets are subjected to heat during implantation Substitution Trivalent Chromium for Hexavalent Chromium Plating A—Anodes: K Graphite (Chloride process) IrO2 or Ta2O5 coated Titanium (SO4 process) B—Parts C—Rectifier F C D—Heat Exchanger E—Lined Tank A A F—Exhaust Hood G G—Freeboard E B H—Thermocouple I— Air Agitation System Critical to Process J—Filtration Required 1-2 micron L H 1-2 turnovers K—Nickel plated Cu bus I D L—Ion Exchange system (for chloride based solution) Trivalent vs. Hexavalent Chromium Plating Processes Advantages: • Lower pollution loading (5-10 g/L of Cr content) • Easier waste treatment (pH Adjust) • Tolerant of current interruption • Avoids worker exposure to Cr+6 • Almost burn proof • High throwing power

Disadvantages: • Thickness is limited (<.25 to 0.5µm) • Color matching, finger print problems • Less tolerant to metal contamination (Ni, Cu, Zn, Fe) • More expensive to apply - = Cr+3 Plated Motorcycle • Corrosive ions (Cl , SO4 ) Exhaust Pipes • Poorer Corrosion resistance (when applied over <0.00025” nickel) • Slow plating speed (sulfate process) • No viable commercial hard chrome process Substitution Electroplated Tin-Cobalt for hexavalent/trivalent chromium • Non-chromium alternative to decorative chromium plating • Applied over bright nickel • Appearance identical to decorative chromium • Excellent covering power • Does not provide significant wear or corrosion resistance − A 2 minute soak in 3.5 g/L chromic acid at 60-70°C can increase the level of corrosion protection • Solutions are proprietary - Formulations and alloys produced will vary • Example formulation: Composition* (g/L) Cobalt salt 40 Tin salt 5 Conductivity salt 5-10 22%Sn-78%Co Deposit

*Courtesy of MacDermid-Enthone Inc. Photo by F. Altmayer

Tin-Cobalt Operating Conditions: pH 7.8-8.5 CCD rack 0.3-0.5A/dm2 @6-8V CCD barrel 0.1-0.2A/dm2 @12-15V Temperature 40-50°C (104-122°F) Temp Max: 60°C (140°F) Anodes 304/316 stainless Agitation Mechanical (No air) Filtration 1 micron/carbon Important Contaminants: Copper dark in LCD @ >50ppm Nickel dark deposits @>300ppm Sn+4 dark deposit @>3,000ppm

Properties: Which wrench is Sn-Co plated? Thickness 0.2-1.0µm

Hardness HV100 400- 450 Photos by F. Altmayer Substitution Copper-Tin-Zinc for Nickel • Known as White Bronze, Bright Alloy, Albaloy, Miralloy, Optaloy  • Cu (55-60%)-Sn (25-28%)-Zn (14-18) Features: – Bright – Solderable

– Hardness > nickel (up to 600HK25) – Non magnetic – Effective diffusion barrier between gold Spring loaded washers for and copper electronic terminals, bright alloy plated – More abrasion resistant than nickel – 35% the conductivity of copper Photo by F. Altmayer

Substitution Copper-Tin-Zinc for Nickel Drawbacks: • Plating solution contains cyanide • Solution chemistry & alloy composition are very difficult to control • Higher operating temperature • Frequent carbonate removal is required

Solution (g/L): Operating Conditions:

• Copper Cyanide 3.25 • pH 12.6-13.0 • Zinc cyanide 2.0 • NaCNF (g/L) 2.5-3.0 • Sodium stannate 1.65 • Volts (barrel) 5-6 • NaCN 22.5 • Volts (rack) 3.5-4.5 • Na2CO3 30 • CCD (rack) 15-20 • NaOH 4.5 • Temp. (rack) 60-65°C • Brightener As req. • Temp. (barrel) 65-70°C • Anodes 55/30/15 Alloy with 75% of area Steel Substitution Cr+3 Chem Film for Cr+6 Chem Film • Developed by US Navy

• Mixture of Cr+3 salts and metallic fluorides

• Solution operates in a steady- Coating state condition

• Coating weights of 20-25 mg/ft2

• 7-15 g/L, pH 3.5 – 4.0, 18-50°C, 3-5 minutes Top: Aluminsecent® (Luster-on), photo by F. Altmayer Bottom: Interlox ® (Atotech), photo • Stand-alone or Paint base courtesy of Atotech USA Not Shown: MacDermid-Enthone Iridite ® 400 Substitution Neutral non-cyanide silver for alkaline cyanide silver Commercialized Types: • Alkaline succinimide • Alkaline methane sulfonic Advantages: • Harder (120-130HK25), more wear resistant vs. cyanide deposits • Avoidance of cyanide Possible Drawbacks: • The deposits from some solutions may have a yellow cast, especially at low current densities • Not amenable to high speed (reel-reel) plating due to low current densities employed • Some solutions require copper strike over nickel based alloys • Incorporation of organics may produce blow-holes during soldering • More stressed and prone to rapidly tarnish • Complex chemical make-up makes control of some solutions difficult

Substitution Neutral non-cyanide silver for alkaline cyanide silver

Solution Make-up Concentration • Silver Ions

(complexed with 5,5-dimethylhydantoin, C5H8N2O2 ) 25 g/L

• Sulfamic acid (NH2SO3H) 52 g/L • Potassium hydroxide (KOH) 60 g/L

• 2,2’-dipyridyl (C10H8N2O2 ) 0.8 g/L

Operating Conditions: pH 7.5-9.0 Temperature, °C 10-38 Current Density 0.2-2.0 A/dm2 Anodes Pure Silver or inert Anode/cathode ratio 1:1 to 5:1 Anode current efficiency 70-90% Cathode current efficiency 85-98%

US Pat. 10,785,297, 2004 *granted to Technic Inc. Substitution Neutral non-cyanide silver for alkaline cyanide silver

Solution Make-up Concentration

• Silver Ions (as AgSO3CH3) 10 g/L

• Methane sulfonic acid (CH3SO3H) − Neutralized with KOH 10-15g/L

• Cysteine (HO2CCH(NH2)CH2SH) 5 g/L

• Borax (Na2B4O7·10H2O) 20 g/L

• 2-nitrophthalic acid (O2NC6H3(CO2H)2) 2 g/L

• Nicotinic acid amide (aka Vitamin B3) 25 g/L • Tegotain 485 surfactant 3 mL/L • Brightener (1% solution, sulfone derivative) 0.1 mL/L Deposit exhibits Operating Conditions: excellent color/brightness. pH 9.5-10.5 Adhesion over brass and bright nickel is Temperature, C 25-30 excellent Current Density 0.3-1.0 A/dm2 Anodes Pure Silver

* US Pat. 6620304B1 granted to EAB-Oberflachentechnologie GmbH Substitution Non-cyanide copper for cyanide copper Applications: • Heat Treat stop-off • Plating of: − Zinc die castings − Strike for steel − Zincated aluminum Advantages: • No Cyanide • Mild pH (9-10) • Lower operating temperature Disadvantages: • More troublesome than cyanide process • Higher operational costs Alkaline Non-Cyanide Copper Plating Solutions

Component Conc., g/L Copper ion 6 - 9 Iron 1.0 max Operating Conditions pH 9–10 Anode/Cathode 1:1 to 1.5:1 Anode baskets Titanium Temp, °F 100–140 Filtration Continuous, 5 micron, 2-3 turns Carbon Pack Required CCD 15–30 A/ft2 ACD 5–20 A/ft2 Agitation Air Comparing Cd Alternates Salt Spray Performance: Plated Deposit Hrs. to White Rust Hrs. to Red Rust Cadmium (bare) 672 >1000 Cadmium + Chromate 672 >1000 Zn-Ni (acid chloride) 168 336 Zn-Ni (alkaline) >1000 >1000 Zinc-Cobalt (acid chloride) 168 336 Zinc-Cobalt (alkaline) 336 672 Tin-Zinc 672 >1000 Hydrogen Embrittlement: Plated Deposit ASTM F519 Cadmium (bare) PASS Cadmium + Chromate PASS Zn-Ni (acid chloride) FAIL (alternate vendor passed)

Zn-Ni (alkaline) PASS Data from Zinc-Cobalt (acid chloride) FAIL Tinker AFB study Zinc-Cobalt (alkaline) FAIL Tin-Zinc FAIL Substitution Alkaline Non-Cyanide Zinc-Nickel for Cyanide Cadmium

Features: • Low Hydrogen Embrittlement (when plated w/o brightener • Excellent throwing /covering power • Higher level of salt spray performance vs Cd • Excellent corrosion resistance at elevated temperatures • Chromates relatively stable at high temperatures • High abrasion resistance • Favorable galvanic couple with aluminum Photo By F. Altmayer Substitution Alkaline Non-Cyanide Zinc-Nickel for Cyanide Cadmium

Drawbacks (vs. Cadmium): • Lower level of lubricity • Tendency to produce pin- blisters • Troublesome plating process uses insoluble anodes • Presence of nickel chelate poses potential for wastewater treatment issues Pin blisters on bearing race

Photo By F. Altmayer Alkaline Zinc-Nickel Plating Solution: Zinc Metal: 8.8-11 Nickel Metal: 0.9-1.1 Sodium Hydroxide: 130-160 Sodium Carbonate: 0 - 60 Complexing Agent*: as required Anodes: Nickel or Nickel plated steel CCD: 30-60ASF ACD: 80 ASF max Note: Dummy new solutions (3 ft2 of dummy area/100gallons) at 2-3 ASF for 24hr.

* Complexing Agent Example: diethylene triamine (DETA) Substitution Citric Acid Passivation of SS for Nitric/Chromic Acids Process: A Citric acid solution is used to remove free iron from thoroughly cleaned stainless steel

Features: • The process replaces more dangerous and environmentally more harmful acids • Free iron is removed from the stainless steel • No fumes/mists generated • There is no measurable dimensional change Drawbacks: “As manufactured” stainless steel tank • No oxide film is produced by the process − Oxidation is slowly produced by exposure to air • Some users have reported trouble meeting corrosion resistance requirements • Citric acid poses wastewater treatment issues Passivation of Stainless Steel Processes

Important to Control: • Temperature (within +/-2°F of optimum) • Immersion time (within +/- 10% of optimum) • Chemical composition (within +/-10% of optimum) • The pH of the final rinse (6-8, preferably 6.5-7.5) Substitution Biologic Soak Cleaners for Alkaline Soak Cleaners Process: • Water based degreasing/cleaning system using bio-organisms that consume oils/fats • Suitable for parts cleaning prior to plating, painting, powder coating or hot Biologic soak cleaner dip metallizing • Control unit adjusts solution temperature, pH levels and surfactant concentration • Bacteria require carbon (oil), nitrogen and phosphorus (supplied by the control unit), along with oxygen • By-products produced are carbon dioxide, water and inert solids • Cleaning cycle time is 5-8 minutes Control Unit Photo courtesy of Bioccelate USA, Bristol RI

Biologic Soak Cleaners Features: • Operates at 104°-122°F (no ventilation) • Essentially eliminates cleaner dumps/waste treatment • By-products produced are carbon dioxide, water and inert solids • Used in Europe/USA for several years • Consumes oil at a typical rate of about 5lb./8 hr. of operation • Operates at near neutral pH (8.8-9.2)

Drawbacks: • Low pH/high temperature tends to reduce the efficacy of the surfactant • Bacteria become dormant at elevated pH/low temperatures • Bacteria are destroyed by high temperatures • Lubricants consumed are limited to aliphatic hydrocarbons, aromatic hydrocarbons (up to 5 rings), partially chlorinated oils and traces of chlorinated solvents • Payback may be >2years Extending Cleaner Life Lipophilic Filtration

Cleaner Filter

Upon Heating to 150oC (300oF) Lipophilic Filter Filter Media Removes Oil Dissolves Into Oil Continuously to Creating a Fuel <10 ppm Experience with Lipophilic Filtration

Time of Test* Oil Content (by Start-up—Cleaner 2 extraction) weeks in use 2 weeks later 4,000 ppm 2 weeks later 50 ppm 2 weeks later < 5 ppm 2 weeks later < 8 ppm 2 weeks later < 5 ppm Total 10 weeks < 5 ppm Filter out of service at 11 + weeks * Intermetro Industries Inc.

Substitution Inhibited Acids for Non-inhibited Acids Benefits: 30 min 60 min • Reduces metal attack 90 min • Enhances cleaning 120 min • Mitigates hydrogen embrittlement 150 min P2 Benefits: Inhibitor A 30 min • Less acid used/disposed 60 min • Reduces percentage of rejects 90 min • Reduces air emissions 120 min 150 min Drawback: Inhibitor B • Can cause plating adhesion issues Inhibitors vary in efficacy Impact of Inhibitors On Acid Pickling Times

Notes:

• Addition of a depolarizers such as manganese dioxide can improve pickling efficiency by reacting with evolved hydrogen gas

• Depolarizers can reduce pickling time by up to 30% Extending the Life of HCl by Aeration

Process: • Air agitation in HCL pickle oxidizes some of the ferrous ions to the ferric state • Ferric oxide becomes an insoluble solid • Precipitated solids are removed through continuous filtration • Acid is “rejuvenated” Benefits: • Acid life is extended Drawback: • Increased acid mist produced adds to scrubber load Substitution UV Curable Masks for Waxes, Paints, Volatile Solvents Process: • UV curable resin hardens in seconds to produce an adherent maskant film upon exposure to UV light • Resin changes color (blue to pink) to confirm proper exposure/cure • One version of maskant is peeled from the surface after use, leaving no residue on the surface

Applications: • Acid Based Stripping • Anodizing • Plating (including EN and Hard Chromium) • Chemical Milling • HVOF/Plasma Spray • Painting/Powdercoating • Blasting/Shot Peening/Vibratory Finishing Photo courtesy of Dymax Adhesives & Light Curing Systems Substitution UV Curable Masks for Waxes, Paints, Volatile Solvents Features: • Masking takes seconds vs. hours for alternative methods • Excellent adhesion to most metal surfaces • Little or no use of volatile solvents • Maskant waste is non-hazardous • Low energy consumption • Eliminates/reduces use of: − Waxes − Solvents − Chemical strippers Drawbacks: • Expensive equipment • Complex shapes may be difficult to expose to UV Photo courtesy of Dymax • Trial and error required to develop the Adhesives & Light Curing technique Systems UV Curable Masks Burn-Off Masking Resins • Best surface adhesion • Greatest resistance to heat/aggressive chemical solutions • Secondary heat curing capability • 900°F to 1400°F (~15 minutes) • Maskant is incinerated leaving no residue

Peel-able Masking Resins • Good adhesion • Resilient enough for grit blasting, shot peening, acid cleaning, plating and anodizing • Removed through by peeling • Cured in a few seconds with UV light • Can be used in multiple process steps • Maskant waste is non-hazardous Photo courtesy of Dymax Water Soluble Masking Resins Adhesives & Light Curing • Used in "dry" finishing processes such as grit blasting, Systems grinding, shot peening, and plasma spraying • Maskant dissolves in hot water (140° - 180° F) and a spray wash or agitated/ultrasonic bath • Maskant completely dissolves in the water leaving no residue • 20% maskant in water has a pH of 7 The End, Break Time!