I said I would (eventually) acquire a tub of this acrylic putty and report on it. I was hoping that the word “hard” meant “hard” like auto-body putty (Bondo) or regular model kit putty (Green Stuff?) but “hard” in this case means hard like a bar of soap or hard rubber. It’s possible to sand and file it, but you’ll never get a “mirror” finish on it. It’s a different type of material.
In truth, it’s not that different from the regular “Golden Molding Paste” that I had when I bought this for comparison. Now I have what is basically two tubs of the very similar stuff. It may be harder than the other paste, but it’s not that much harder.
So it’s not a filler putty that you can use the same way you could use Squadron Green Putty. It is possible to sand and file it, but it’s still going to be like soap or hard rubber.
The beauty of this product is that you can smear it on, smooth it with your finger, and then paint it. In less time that it took me to say it, you can fill a seam and cover it with acrylic paint. You can mix it with acrylic paint. You can mix it with paint and use THAT for smoothing a seam or adding in a fillet or whatever.
The idea of smoothing and painting in the same operation appeals me. I don’t enjoy sanding and this is one way to fill seams without sanding and so it is a good thing. Sanding–who needs it?