No bother and good question. The method you’re talking about is what people use to seal the foam and is often something you do BEFORE painting. Whether or not you seal the foam and how you do so is really up to you and what all you’re doing to the foam. For my own foam to leather process, I did not put anything on the foam itself (before painting) or over the paint. The reason for this is because of the following:
- Applying heat to the foam melts the outer layer so that the foam is no longer porous. This process seals the foam (to an extent).
- The paint won’t flake off or smudge. The idea for that tutorial was to get the black paint in the grooves left behind by the aluminum. With the paint tucked away in those grooves, I would be very surprised if the paint were to get ruined in some way.
- If some of the paint does rub off, no biggie. It just looks like wear and tear.
I’m not saying that you should never seal your foam with anything but an iron or other heat source. Certain paints (such as many spray paints) will actually degrade the foam. In such cases, it is VERY important to seal the foam by putting a layer of sealant on top of the foam before applying paint. These sorts of sealants come in many forms. Some people use Elmer’s glue, some modge podge, some use acrylic sealer; it’s your choice.
Now, to really answer your question (sorry about the rant above), if you’re really worried about damage, then yes, do seal the paint. However, I would not recommend using glue. Elmer’s glue by itself tends to be too thick and it leaves the foam looking shiny. I know of a few people who dilute it with water but the process is messy and I personally think the outcome doesn’t look professional. Personally, if I’m worried about paint getting chipped, I use acrylic sealer. It’s not very expensive, you only have to coat your foam once (maybe twice, for luck), and it comes in matte AND glossy (so you can pick between the two depending on what the paint finish should be). In this case, I would recommend a matte finish.
Final thought: IT’S YOUR PROJECT; DO WHAT YOU FEEL IS RIGHT. I can give you all the advice in the world, but, in the end, this project is your baby and if you fear sharp edges may mar your beautiful creation, slap some sealer on there.
I hoped this answered your question. I would love to see the outcome of your project, btw. I’m sure it looks amazing. ❤