Mixing and Spreading the Filler

Okay, so now you have the board prepared and ready for the filler it's time for the mucky and smelly bit.

It's worth mentioning before you start that car body filler really stinks. It's a solvent based product that smells until its hardened, so it's best to do this outdoors or suffer the wrath of the better half. I do mine under the veranda.

Also worth mentioning is the speed at which the filler will go hard given the right conditions. Basically the warmer the air temperature the faster it hardens. On a summers day expect the filler to go hard in under 3 minutes. In the winter this can be upwards of 20 minutes!

I find it best to mix and fill in a colder environment and then heat it up with a hair dryer or in the airing cupboard.

So the filler comes in two parts, the main filler in the tub and the hardening compound in a little foil tube. Start by getting hold of an old magazine to mix on. That way once the left over filler is hard you can tear off the page and lob it away.

Glop out a big fat blob of filler about the size of a golf ball and smear it onto the magazine. Next squirt out some hardener about the size of a pea. (Use that ratio for all mix amounts). Mix the two thoroughly using your spreader/spatula for about 30 seconds.

Then take a small amount and spread it thinly onto your board. Make sure the filler is applied evenly to the masking tape bed, ensuring there are no air bubbles. Remember, this is the face of your brick and needs to be the neat part! Once you have covered the area evenly leave it to dry for 15 minutes.

Once dry, it can be sanded slightly ready to take the main fill on the top. This fill needs a fair bit of filler - perhaps three times the amount you used before. Fill up the remaining depth to the level of the ply, then leave to dry again.

It should now look something like the image above.  The second fill does not have to reach past the ply. Simply add the filler in 3 or 4 layers if you wish until the filler is above it. This 5mm is optimum thickness to aid robustness.

Now sand the filler down to the ply level with an 80 grit like so:

This has also been marked out using the paper template ready for removal.

Now this is the dangerous bit as the piece needs to be removed withou scratching the nice textured face hiding underneath. I peeled up the edge of one side of the masking tape and slid a large kitchen knife under it and gently pulled up the tape/filler away bit by bit. Eventually the piece will pop off the board. Remove the tape and you will have this: 

Use your handsaw to cut out the shape, you will find it cuts very nicely but beware - it can be brittle if manhandled heavily. The rough edges can now be sanded down and tidied up.

Next step is the most rewarding but yet the most monotonous. 

Scribing.....!