EM121 is a two pack modified epoxy high build coating.

It comprises base colour component A, and an equal amount of hardener component B.

Mix components A and B together in equal amounts, e.g. 100ml A to 100 ml B by measure. Allow to stand for approximately ten minutes to allow the chemical process to start.

All of the data on our technical data sheets are calculated at 23 degrees C. If the ambient temperature causes the Epoxy 121 to be a higher temperature the product will be thinner. At low temperatures the product will be much thicker and possibly almost paste like.


EM121 can be thinned up to a maximum of 15–20% with the thinners provided in each kit. For spraying or fine brushing you will definitely need the thinner.

By brush

Depending on the temperature at the time of application, EM121 can be easily brush painted. You may find that you don’t require thinner, but you can add up to 15% thinner. Use a fully loaded wet brush and long strokes for the best finish.

Top tip: using EM121 as a surface filler. Without thinning, EM121 can be brush-applied as a filler coat for imperfections on steel surfaces of up to .5 of a mm thick (500 um/microns). Mix equal amounts of component A and component B without adding any thinner, allow to stand for ten minutes, and then brush onto the surface. Scrape away excess to level the surface.

By roller

EM121 can be applied by roller: load the roller up fully before applying to the surface. Roller application typically requires twice the amount of coats to eradicate the chance of any misses (holidays) in the coating.

By air spray

Use a spray gun with a 1.8 tip size (smaller tips can be used on gravity fed spray guns). Thin the product up to a maximum of 20% with the thinner provided, although less may be required.

Over painting

EM121 can be overpainted with any paint product. If fully cured (after approx. one week) a light sanding with a 320 grit abrasive will be required prior to painting. This also applies when painting a second coat of EM121.

Seam sealing

Apply EM121 to the bare steel area first, A seam sealer, preferably polyurethane, can then be applied over the EM121 to seal the seam.

Filling over EM121

Due to the very hard nature of EM121 when cured, we would recommend a sanding with an 80 grit abrasive and filling with PC-7 epoxy paste.



These ‘how-to’ guides are not technical data sheets or health and safety data sheets. These can be downloaded from our data sheet page. Any other technical information on drying times etc. is available from the data sheet.

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