Is this foam the German Styrodur brand?

No, that brand is not available in North America. This is a very similar product, and has comparable characteristics. It was chosen to be the best possible alternative for hobbyists in North America.

What is the difference between the various PSIs?

The PSI of foam represents its compressive strength. The lower the number, the more elastic the foam is, and more easily it will “bounce back” to it’s original shape. One problem with the XPS foam readily available in North America is that it is limited to one specific PSI which is lower than ideal for hobby purposes. The higher the PSI the better the foam will retain impressions from things like textured rolling pins. The higher the PSI the crispier your details will be when texturing or carving the foam. 

Why offer lower PSI foam if the higher stuff is better?

Cost vs use. The higher the PSI of the foam, the more costly it is. There are many hobby applications where the advantages of a higher PSI foam would be irrelevant. While high PSI is great for carving or rolling intricate details, it is not needed for carving organic shapes like rocks. For these purposes the lowest PSI foam will be sufficient and there is no reason to use the more expensive material for these tasks. 

How does this foam compare to Foamular that I can buy at Home Depot?

The higher PSI foams offered here are exceptionally better at holding rigid detail than the Foamular you can buy at the retail level. Even the lowest PSI foam offered here is denser and better at holding details than the Foamular you can buy in store. In addition to compressive strength for carving, this foam is offered in a variety of thicknesses that are ideal for hobby purposes but rarely, if ever, available at the retail level. 

Can I spray paint this foam? Will it melt?

All XPS foam is susceptible to melting from the solvents in spray paint. There are variables that affect how vulnerable foam is to melting (spray paint brand, foam brand, distance sprayed from, amount sprayed). While I have personally found that you can spray paint foams safely if sprayed with a less aggressive paint, from an adequate distance, one of the properties of this foam in particular (much like the Styrodur foam) is that it does not take spray paint as well as some others. While it is not prone to extreme melting, it tends to melt slightly into a rough texture that absorbs the spray paint resulting in poor coverage. I recommend priming/painting this foam with acrylic paint through an airbrush or by hand. 

Do I need to seal this foam with something like Mod Podge?

That is up to you. I personally don’t unless the build has many very small pieces of foam that could easily fall off over time. This foam is already harder than the Foamular or DOW foam you may be used to using, so it “feels” denser on a finished build, with a harder surface. Mod Podge will not protect any foam from taking impressions if dented, so for this foam there is little reason to coat it before paint, unless you want to spray paint it after. In that case it can be beneficial to help it better accept spray paint. 

How can this foam be cut?

With the same tools you would use on any other foam. Hotwire, knives, and saws. It can also be sanded with abrasives like files or sandpapers. 

Is this foam safe to cut or sand?

When cutting any foam with hotwire tools it is important to ensure you have your temperatures and cutting methods dialled in to melt the foam rather than burn it (which causes black smoke). Even with proper cutting methods, cutting of foam with hotwire tools should be done in a well ventilated area. If ventilation is not adequate, or you want to take extra precaution, wearing a respirator rated for organic vapours is recommended.

Dust and fine particles created while sanding foam should not be inhaled. A dust mask should always be worn when doing this, and dust cleaned up thoroughly afterwards. 

Is this actually the SAME foam Black Magic Craft uses?

Yes! This is the foam I have been using exclusively since I found and sourced it!

Happy Crafting!

Jeremy

Black Magic Craft