Applying the finish

Having sanded the whole frame down to 240 grit it was time to apply a finish. Though my intention was that the first bicycle would be a summer, fine weather bike, I still wanted a hard wearing and fully waterproof finish. I decided to use epoxy overcoated with a 2K polyurethane. 

The tech guys at West System gave me good advice on applying their product as a finish. Instead of using the 205 hardener that I used for the glueing, they suggested I use 207, which is very close to clear and less 'yellow'. It also also has some UV inhibitors to prevent yellowing over time. The 2K polyurethane would have further UV inhibitors, be fully waterproof and allow the frame to be polished to a high gloss.

Prior to applying the finish I fixed on some vinyl decals that I had printed. I applied the epoxy using a brush.  The pics below show the biccyle frame prepped and the bike frame with its first coats of epoxy. It was exciting to see the richness of colour of the brown oak coming into its own.

Bike frame prepped for finish

Bike frame with first coats of epoxy

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I applied two coats of epoxy, tack on tack, then left it for 48 hours. I then sanded the epoxy using 120 grit, being very very careful over the decals. As well as smoothing out the uneveness of the brush applied epoxy it is important to sand the epoxy back to 'dull' as a key for the next coats. I repeated the process, applying two more coats of epoxy, tack on tack and left the frame for another 72 hours before sanding back with 240 grit.

 

Bike frame being sanded

 

Once the frame was sanded back smooth it was time to apply the polyurethane top coats. I intended to spray the polyurethane to minimise the amount of further sanding needed. I used 2K polyurthane as this would give the best protection. I used Joyun Xtreme Gloss. Using a spray gun and compressor I sprayed 4 coats, tack on tack. I left the frame for 72 hours before a light sanding with 1500 grit paper followed by buffing with 3M fastcut.

Once polished, I fitted the frame out with all the components, the key parts of which were a 105 groupset, 28C tyres on 19mm rims.

 

 

 

© Christopher Thompson