To fill a sign with color

There are a variety of ways to do this, and many have their own tricks. It is much more work with this compared to oxidation, but this method should be used for slightly larger engraved texts.

The engraving depth should be around 0.25mm to get a suitable depth for the paint. It is important to have good milling tools when using brass and aluminum so that the engraving is smooth and fine without any burrs around the grooves. If there are burrs around the texts, this makes it difficult to get a good result when filling in the color. It is very important to have some form of cooling when engraving, especially anodized aluminum (alcohol or cutting oil). Clean the sign carefully after milling so that all oil disappears before filling in the color, as this can affect the color!

It is important to blow the sign clean with compressed air or similar so that you remove all the shavings that remain after the engraving. If shavings remain, the result may be worse when filling in the color, and the shavings can also cause scratches in the surface when you then wipe the sign clean.

One way is to mask around the engraved area as best you can with masking tape, and then paint on the color with a soft brush over the text. Make sure there is a good amount of paint in the engraving.

Then carefully remove the remaining paint with a soft rubber scraper or similar. Finally, take a cloth with thinner (the appropriate thinner depends on the paint you are using) and place the cloth around a completely flat block. Then carefully drag the block with the cloth over the masked area with the engraving until the surface is completely clean of the remaining paint. If you do not use a block, it is very easy to get the paint out of the grooves when you wipe the sign.

If you are using anodized aluminum, it is important to remove the remaining paint as quickly as possible, as there can be "shadows" in the surface due to the pores. This applies especially to matte anodized aluminum. Glossy anodized is a little easier as it does not have the same rough surface with pores that the paint goes into.

You can try waxing the surface before engraving and in this way protect the surface from remaining paint. This way you avoid "shadows" due to the agent sticking to the surface.

You then remove the masking and carefully wipe off any paint residue where the masking was. As I said, there are a number of other ways to do this, but this is a simple variant that many people use.