I use a brush and read about sprinkling backing soda over it. The baking soda really helped with the stickyness on the last 2 I did.

In most cases I only use a flexible brush which I bought especially for this work. with most headliners it goes pretty well. With scrapers or similar I always have the impression that the material is pressed into a kind of sticky paste. Sometimes I also take clear water with me. But only if the material is not too absorbent.

With Jens being from Europe where they developed this foam, he knows these headliners well. I do the same thing - if it's a waterproof or water-resistant board (fiberglass, polystyrene), then I use water in the difficult spots. If you immediately blow the area clean with compressed air, you can reduce any bloating that might occur if there's a surface layer of paper. For the really nasty goo, I'll spray 90% isopropyl alcohol and again, blow dry it quickly afterward.

In cases where I could get it smooth but couldn't eliminate the stickiness, coat the board with a PVA-based primer (most drywall primers). Then you'll have a clean, dry surface to glue to.

By the way, Michael Todd, I looked at your company website. I love it! Lots of American auto upholstery history going on there.

Thanks so much for the compliment! We have been trying the baking soda method with great results. It's so hard to believe that something so inexpensive and readily available can be so effective. I would have never guessed in a million years this would work better than all the chemicals we have experimented with. I love this Hog Ring forum!

I have used denatured alcohol in a spray bottle.
It is the only thing that I have tried that dissolves the foam and leaves a clean surface. Sometimes you need to use a razor blade to clean off a hard surface like a sun shade from a Mercedes when doing a headliner replacement. Also PPG DX 106
Surface prep works great for cleaning the orange residue from fabric without damaging the cloth.
It is quite expensive compared to denatured alcohol but it is different.

On the other hand, What Not to use. Don't use 409. It cleans it off easy But it also leaves a film that keeps the new glue from adhering to the surface.