Technical Data Epoxy Mastic 121
Product description Epoxy Mastic 121 is a two-pack surface tolerant high solids epoxy mastic coating which is provided in 1 :1 mixing ratio for easy mixing and reduced wastage.
Epoxy Mastic 121 is applied by Spray brush or roller.
Anticorrosive coating for steel structures.
Epoxy Mastic 121 is suitable for areas with lower quality surface preparation and extended durability is expected.
Film thickness and spreading rate
Film thickness, dry (µm)100 – 400
Film thickness, wet (µm) 115 – 445
Theoretical spreading rate (m²/l) 8.7 – 2.9
Film thickness above is typical for what is achieved by one coat .
Aluminium, Black, Buff, Green, Grey, RedSolids (vol %)*72 ± 2 Aluminium75 ± 2 Black, Buff, Grey, Green, RedFlash point33ºC ± 2 (Setaflash)VOCAluminium
2,51 lbs/gal (300 gms/ltr) USA-EPA Method 24240 gms/ltr UK-PG6/23(97). Appendix 3Colours2,34 lbs/gal (280 gms/ltr) USA-EPA Method 24230 gms/ltr UK-PG6/23(97). Appendix 3
Gloss Level Semi gloss
Gloss retention Fair
Water resistance Very good
Abrasion resistance Very good
Solvent resistance Good
Chemical resistance Good
Flexibility Good *Measured according to ISO 3233:1998 (E)
All surfaces should be clean and free from contamination. The surface should be assessed and treated in accordance with ISO 8504.
Bare steelCleanliness: Power tool cleaning to min. St 2, mill scale free (ISO 8501-1:2007). Improved surface treatment (blast cleaning to Sa 2½) will improve the performance. In case of hydrojetting the flash rust degree shall not exceed moderate in SSPC and NACE standards for water prepared surfaces.Shopprimed steelClean, dry and undamaged approved shopprimer.
Coated surfacesClean, dry and undamaged compatible primer. Contact Rustbuster office for more information. For maintenance UHPWJ to WJ2 (NACE No.5/SSPC-SP 12) or Power tool cleaning to min. St 2 for rusted areasOther surfacesThe coating may be used on other substrates. Please contact Rustbuster for more information.
Condition during application
The temperature of the substrate should be minimum 0°C and minimum 3°C above the dew point of the air. The temperature and the relative humidity should be measured in the vicinity of the substrate. Good ventilation is usually required in confined areas to ensure proper drying. With forced ventilation, avoid heated air at first as this may cause surface drying and solvent entrapment. The coating should not be exposed to oil, chemicals or mechanical stress until fully cured.
Hydrojetting of steel surface makes a wet surface. The surrounding air must have a relative humidity not exceeding 85 %. Before painting the surface shall not be glossy with moisture, but can have a patchy apperance.
SprayAirless 17 - 19 thou tip
Conventional spray thin up to 15% with No17 Epoxy thinners spray tip 1.5 - 1.9
Use a round brush. Care must be taken to achieve the spreading rate.
Use of a foam roller will provide the best hand finish results.
Mixing ratio (volume)1 parts by volume Comp. A (Base) to be mixed thoroughly with 1 part by volume , Epoxy Mastic 121 Comp. B (Curing agent).
MixingMix well and allow to stand (10 min. including mixing).Pot life (23°C)1½ hours
Thinner/ Epoxy Mastic 121 Thinner No. 17Note* The temperature of the mixture of base and curing agent is recommended to be at least 15°C, otherwise extra solvent may be required to obtain correct viscosity. * Too much solvent results in lower sag resistance and slower cure. * If extra solvent is necessary, this should be added after mixing of the two components.
Drying timeDrying times are generally related to air circulation, temperature, film thickness and number of coats, and will be affected correspondingly. The figures given in the table are typical with:* Good ventilation (Outdoor exposure or free circulation of air)* Typical film thickness* One coat on top of inert substrate.
Temperature Surface dry Through dry Cured Dry to recoat min
5°C 12 h 20 h d
10°C 7 h 14 h 14d 24h
23°C 4 h 7 h 7 d 10h
40° 2 h 3 h 3 d 5h
Provided the surface is free from chalking and other contamination prior to application, there is normally no overcoating time limit. Best intercoat adhesion occurs, however, when the subsequent coat is applied before preceding coat has cured. If the coating has been exposed to direct sunlight for some time, special attention must be paid to surface cleaning and mattening/removal of the surface layer in order to obtain good adhesion.The given data must be considered as guidelines only. The actual drying time/times before recoating may be shorter or longer, depending on film thickness, ventilation, humidity, underlying paint system, requirement for early handling and mechanical strength etc. A complete system can be described on a system sheet, where all parameters and special conditions could be included.
Handle with care. Stir well before use.
Packing size5 litres Comp. A (base) 5 litres Comp. B (curing agent) in 5 litre containers.
Health and safetyPlease observe the precautionary notices displayed on the container. Use under well ventilated conditions. Do not breathe or inhale mist. Avoid skin contact. Spillage on the skin should immediately be removed with suitable cleanser, soap and water. Eyes should be well flushed with water and medical attention sought immediately.For detailed information on the health and safety hazards and precautions for use of this product, we refer to the Material Safety Data Sheet.
DISCLAIMERThe information in this data sheet is given to the best of our knowledge based on laboratory testing and practical experience. However, as the product is often used under conditions beyond our control, we cannot guarantee anything but the quality of the product itself. We reserve the right to change the given data without notice.