Coating Metal Cups:
- For engraving, no coatings are strictly necessary. However, a clear non-yellowing UV top coat is not a bad idea because you have scratched the surface of the cup so the remaining paint has exposed edges that could flake off with wear over a long time. One or two light layers of a glossy finish should give you maximum durability.
Coating Plastic Cups:
Coating ink on top of plastic must be done with care. Plastics have chemical resistance which prevents many inks from even marking on them. Consequently, many common coatings for plastics are solvent based to make them more effective but those solvents can melt down your artwork! Look for water-based clearcoats, as opposed to solvent based ones. UV resistant and non-yellowing are also nice features.
Step 1 is always sealing the colors in. We recommend using 2 layers of varnish, with at least 15 minutes between layers. Use either spray on (our preference) or a very lightly applied wipe on with good quality bristle brush.
Best Option = DuraClear varnish wipe on, applied with a clean paper towel with at least 15 minutes of drying time between coats.
Option #2: Krylon Kamar Varnish Aerosol Spray. Apply 2 coats, but never so heavy that it drips.
The next step to apply a sealer.
Again, we get to choose between spraying and wiping. The most universal option is to use 2-3 coats of Modge Podge dishwasher safe sealer. This product is thick and we like to apply it with a clean paper towel very thinly so it will dry clear. If you apply it too thickly with a brush you can introduce bubbles and a noticeable texture.
For maximum durability add a light top coat of Krylon UV resistant clear gloss. (The modge podge will prevent this here but generally beware high acetone content in paints which will dissolve the varnish enough to melt your art!)
Another option is a 2-part epoxy coat. This is a really popular choice crafters use even though it can be messy. Again, epoxy is a string enough solvent to melt your art so you want to protect the cup with layers of the above prior. Also the epoxy must be mixed 1:1 and if the ratio is off it wont fully cure and became sticky. To resolve stickiness I’ve had luck with a spray on epoxy finisher.
Acrylic Sealer tests in progress.
Water-Based Polycrylic Clear Spray. It melted our artwork easily, however it was protective when it dried…
Matte vs Gloss scale.
- Matte is flat, non-light reflecting. It is usually better at concealing imperfections. Gloss is highly light reflecting but it usually offers better protection from fading and chipping.