Cartridge Mixing
It is essential for best results that the cartridge is ‘balanced’ before use to ensure correct mixing. This is achieved by loading the cartridge into the gun before addition of the mixer element and pumping the gun to push a small amount of the contents forward. Wipe the excess from the cartridge tip and add the mixer. The cartridge is now ready for use.

Combustion
Most epoxies and polyurethanes generally ignite above 415°C. 
Decomposition products will consist of carbon, carbon dioxide, carbon monoxide, hydrogen cyanide nitriles and water, and are best avoided.

Curing
Curing is the process by which resins react to produce a solid infusible mass. The reaction of resin and hardener usually involves the liberation of heat called exotherm. This is generally controlled by careful formulation and the addition of fillers and additives that suppress excessive heat build up. It is however dependant on the ambient temperature and the mass of material used. Smaller masses and lower ambient temperature will extend cure time and larger masses and warmer ambient temperatures will reduce cure time. Hotter temperatures may be used for faster cure but will result in higher post cure shrinkage and higher cure exotherm.  Experimentation and testing is suggested to avoid side effects.  For maximum properties a post cure may be required - call Robnor Technical Service Department for advice.

Please consult the technical data sheet before using Resin-Online products.

Disclaimer
The results and information in the technical data sheets do not constitute a specification and is given in good faith and without warranty.  The information is derived from test / or extrapolations believed to be reliable and is quoted for guidance only.  The product is offered for sale on the understanding the customer will satisfy themselves that the product is suitable for his intended purpose by proper evaluation and testing.

Disposal
Provided the resin and hardener have been properly mixed, as per instructions, the resultant material will be chemically inert and therefore able to be land filled; subject to local government regulations. Liquid product that is yet to react should be adsorbed into sawdust, sand, or available inert materials, and then wrapped in polythene for safe disposal and to protect accidental contact.

Evacuation
Mixing under vacuum is the most effective way to prevent air entrapment. Alternatively the mixture may be deaerated under vacuum – allowing at least 200% ullage for the foam to expand. Some systems may benefit from warming but this should be done before adding the hardener. Brief degassing under 5 – 10 mbar improves the mixture homogeneity and enhance the dielectric and aesthetic properties of the resin.

Environmental policy
Robnor Resins Limited and Resins Online recognises its responsibility as an organisation towards the short and long term impacts of its business in relation to the environment, both locally and globally. It is the intention of Robnor Resins Limited and Resins Online to prevent pollution, through the implementation of an Environmental Management System, with a view to continually improving our environmental performance.

Filler or Extender
In some instances unfilled materials may require modification with filler or extender to give certain benefits.

Adding filler or extender will:
        Increase viscosity, i.e. more difficult to fill moulds and evacuate.
        Increase thermal conductivity (except using glass bubbles)
        Increase general mechanical properties but lower impact strength
        Increase dimensional stability
        Increase thermal conductivity
        Increase hardness
        Can make flame retardant (at certain levels)

But will reduce:
        The cost per kilo
        Shrinkage
        Stress on curing

Properties that remain relatively unaffected include:
        Chemical resistance
        Electrical properties

Filler should be added to the resin by the use of a mechanical stirrer prior to adding the relevant hardener. For best results evacuate the mixed product.

Health & Safety
Observe the Health and Safety Instructions by reference to the MSDS and the label on the product. Do not eat, smoke or drink in the immediate vicinity and avoid skin contact and any vapour that may occur during processing.

House Keeping
Most resin products and associated products are potentially hazardous to health. A good standard of hygiene is essential to avoid related health problems. Do not eat, smoke or drink in the vicinity of resin related products and wash hands before and after going to the toilet. For suitable protective clothing go to ‘products’ and click on ‘Safety wear’.

Pigments
Pigments are added to a resin to give a desired colour. In general the pigment is simply stirred into the resin until uniform at a rate of between 2 to 10% by weight. Filled systems generally require more pigment to mask any effect the filler or extender may have. For best results evacuate the mixed product.

Machining
Allow material to fully cure before machining. Machine using these guidelines:

Lathe speed: 150ft/min
Cut: Dry
Tools: Carbide Top Rake 6°(+/- 2°) Side/Front 8°(+/-2°)
Feed Rate (rough): Travel speed .020.  Rough Cut .020-.060
Feed Rate (Finishing): Travel speed .010.  Finish Cut .010
Polishing: Use 400-650 grit emery paper wet.

Use suitable dust extraction as necessary.

Metal bonding
Thoroughly clean the surface with a suitable solvent to remove all grease, oil and dirt. Grit blast surface area with 8-40 mesh grit, or grind with a course wheel or abrasive disc pad to create increased surface area for better adhesion (CAUTION: An abrasive disc pad can only be used provided white mesh is revealed).  The desired profile is 3-5mil, including defined edges (Do not ‘feather-edge’ epoxy).  Note: For metals exposed to seawater or other salt solution, grit blast and high pressure water blast the area, then leave overnight to allow any salts in the metal to ‘sweat’ to the surface. Repeat blasting to ‘sweat out’ all soluble salts. Perform chloride contamination test to determine soluble salt content (should be less than 40ppm). Clean the surface again with a suitable solvent to remove all traces of grease, oil, dust, or other foreign substances from the grit blasting. 

Repair surface as soon as possible to eliminate any changes or surface contaminates

Mixing Bulk or Kits
Using suitable protective clothing, pour the resin into a mixing vessel and add the correct quantity of hardener. Small quantities may be mixed by hand, i.e. a stick or spatula, and larger quantities should be mixed with a mechanical device e.g., a paint stirrer.
Some systems contain inert filler that may settle during storage. This is called sedimentation.   If sediment is found it is essential the sediment is re-dispersed in the original container before being used.  Failure to do so may result in defective product.  Long-term sedimentation will be aggravated by storage above 25°C and should be avoided.  Light sediment may be re-dispersed by gently mixing with a paddle or spatula.  In bulk or kit form evacuation may be necessary after mixing for best results.

Mixing of Three Part systems
Pour the pre-weighed hardener component into the resin vessel and drain thoroughly. Mix the resin and hardener components thoroughly by hand using a broad bladed implement or preferably mechanically with a paint stirrer on slow speed. (Approximately 1-2 minutes).

Add approximately half the contents the extender / filler and stir.  When the mix becomes even, add the remaining filler / extender and continue mixing for a further 1 – 2 minutes.

Stir well until the material becomes homogenous, paying particular attention to the sides and bottom of the container, as this is particularly important. (Low viscosity mixes will take less time and more viscous products may require more time. If in doubt continue mixing).

Mixing time will also depend upon the temperature of the system and size of the kit. 3-5 minutes would be an average; however operator experience can reduce the time. The rule, however, "if in doubt - mix again" as insufficient mixing will result in soft spots of uncured material that may lead to product failure.

For best results, mix and pour the material before the usable life of the system.

Dispose of the empty kit containers in accordance with local authority requirements. Any excess material that has been properly mixed and cured can be classed as inert and safe.

Moulding and Casting
The use of a vacuum minimises the risk of air entrapment during mould filling and the resin mixture should enter the mould in a steady steam. Fore best results the mould should be vented to avoid air entrapment and voids. Warm moulds generally give better castings.  In general when using epoxy and polyurethane materials the mould will need to be treated with a mould release agent. The quality of the moulding is largely determined by the choice of casting material and the quality of the mould finish.

Post Curing
In many resins the performance of the system can be enhanced by a process called post curing. This involves a secondary cure process over and above the normal conditions to provide enhanced performance. In general post curing will improve such properties as; chemical resistance, temperature stability, dimensional stability, voltage breakdown resistance, water resistance and increase glass transition temperature. Post curing is mainly used on epoxy systems but can also be used on some high performance polyurethanes to enhance them still further. In general post curing occurs at 10 – 20.C above the maximum expected service temperature.

Typical post curing (depending on system), may involve a normal cure plus:

        16 hrs at 100.C or
        8 hrs at 120.C or
        4 hrs at 140.C or
        2 hrs at 150.C

Pot life
This is the time to double the initial mixed system viscosity.

Primers
A properly prepared substrate is essential to achieve consistent bond performance.

A suitable solvent or cleaning agent prior to the application of the primer should remove all oil, grease and other soluble material from the substrates.

Rust or scale or other lose debris should also be removed by mechanical or chemical methods.

Grit blasting, mechanical abrasion or chemical etching will aid the adhesion of the primer to the substrate, and will significantly increase bond strength.

Primers can be applied by; dipping, brushing or spraying.

Spraying may involve the dilution of the material with a suitable solvent

Contact: Technical Support on 01793 823741 or support@robnor.co.uk for details.

Robnor primers have been formulated to provide optimum bond strength with one coat.
Thick primer layers generally result in lower bond strength.       

In summary:

1. Degrease
2. Abrade (for best results)
3. Degrease
4. Apply primer
5. Allow primer to dry to just tacky (approximately 40 - 90 minutes @ RT)
6. Cast PU and allow material to cure

Spillage & Cleaning
All equipment contaminated with mixed material should be cleaned before the material has hardened.  Robnor Resins TS130 is suitable non-flammable cleaning agent, although other solvents may be found suitable.  TS130 will also remove cured material provided it is allowed to soak for a number of hours.

Storage & Shelf life
Most products stored in the original unopened containers will have a shelf life of at least one-year if stored in dry conditions between 10 and 25°C.  (See expiry date on container or package)
Once bulk containers have been opened the containers must be kept sealed to prevent effects from water, air or contaminants. Temperature below 10°C and above 25°C for long periods should be avoided.

Troubleshooting

Sedimentation: Mix material until homogenous before use
Soft or sticky areas: Poor mixing
Streaks in surface: Poor mixing or casting too warm
Crystallisation (1): Low storage temperature
Crystallisation (2): Material beyond shelf life
Material softer or harder than normal: Check mix ratio
Slow cure speed: Warm gently
Fast cure speed: Cool gently or add filler
Excessive shrinkage: Cast material in several hits
Leaking Containers or packaging: Do not use. Ask for replacement
Excessive bubbles or air entrapment: Evacuate material or pour warm
Material is too viscous: warm material gently before mixing
Mould leaks material: Seal with latex mask
Material sticks in mould: use release spray

Twinpack Mixing
Twinpacks are pre-weighed resin and hardener contained in a tough flexible film, separated by a removable clip and rail.  Once the clip and rail is removed the resin and hardener can be thoroughly mixed within the bag and is then ready for use.  Mixing will normally take ~ 3 minutes depending on the operator and viscosity of the material.  Twinpacks are ideal for small to medium production runs, prototyping and on-site or field use.  

Usable life
This is the time normally in minutes that the mixed resin is ‘usable’.

Varnishes and Coatings
Many objects may be coated using Resin-Online varnishes and coatings either by dipping, brushing or spraying. Pneumatic guns should be used at room temperatures. Drainage retention on steel sheet is in the region of 3% with a non-diluted varnish. When coating a diluted varnish (15% dry extract), the thickness is about 15 to 20 microns.

Viscosity
Viscosity is the resistance to flow. A high viscosity resin has high resistance to flow e.g., treacle. A low viscosity resin has low resistance to flow e.g. water.

Weighing
For best results the resin and hardener must be mixed to an accuracy of +/- 2%. Use the mix ratio stated on the technical data. Do not deviate from the stated ratio as this may have an adverse effect on the properties and cure time.

Working life
This is the time normally in minutes that the mixed resin is ‘workable’.