FWIW, apparently the best attachment method for PP is a heat weld. I’d love to try making some boxes with mostly bent edges…
2 Likes
We use hot air welders here(in the middle of a unit right now). You tack with one attachment then use a different attachment with a welding rod to weld together. The tacks hold very nice but are easily cracked, you need to truly weld it to get a bond.
I would be interested to know if we defocus the laser if parts could be tacked with the GF.
There really no good glues for PolyP.
4 Likes
DO you need a special welding rod, or can you just cut pieces?
1 Like
I like glass cutting boards for pastry stuff. Pie crusts and the lot. Not so much for knife work.
So what you’re saying is that you like glass sheets for pastry work since you don’t cut anything on them. :v
3 Likes
A lot of our truck mudflaps are made of polypropylene. I have access to a seemingly infinite supply of 1/4" and 5/16". I envy your 1/2". There are some issues with cutting polycarbonate. @jkopel shared this ages back but I’ve saved the pdf. @jkopel’s post
Your sheets of polypro are going to be excellent for creating all sorts of housings, boxes, containers, jigs, templates, engraving stamps etc… You’ve got a treasure trove of material!
6 Likes
Could you use the stuff (mainly 1/4" I suppose) to make architectural models and dollhouse miniatures? I’d love to try. Another possible use is custom jewelry displays for retail and art shows.
1 Like
Polypro is dense and heavy. You can use it for these things, but be wary of the weight and difficulty when gluing as it will not accept any glue that I have been able to find so far.
1 Like
I used PP sheets to line my battery boxes on my car (forum avatar). It is very smooth and slippery. I had to “weld” the sheets together with a hot air welder. It helps if you rough up the surface with sandpaper to give glue or silicone something to hold on to. I have some 1/8" sheet leftover and this thread has me wondering if there is something I can use it for. - Rich
1 Like
No doubt, resistant to battery acid. Now I have to wonder about hydrofluoric acid and if you can make a human body-sized tub out of the PP scraps.
edit: I’ve been watching too much TV.
4 Likes
They use it extensively here in the silicon fabs. It is resistant to all acids and is easy to clean. A tub out of scraps? Heh, heh…I’d like to see that…you good at hot air welding? 
- Rich
1 Like
I believe the rod is made of PolyP, as only same plastic can be welded to same plastics. I’ll ask around this afternoon as that is a good question. It seems a lot more flexible and easier to melt then the solid sheets we get in. It’s about 1/8 inch round ish, kind of flattish on one side.
3 Likes
So asked around today. The answer is yes you can just use really thin strips as welding rod. Apparently when we have odd plastics that need to be attached or odd colours we just do that.
3 Likes
Thanks! Convenient in a process where you’re pretty much bound to have offcuts.
1 Like
As for coloring it, try alcohol inks. Basically it’s like watercolors for super smooth, non-absorbent surfaces. Even better is that it can be made super cheaply by recycling old markers with rubbing alcohol.
8 Likes
That sounds awesome about the dyes. I have tons of alcohol and markers are easy.
3 Likes
How have I missed this technique?! Wow, I wonder how many pens I can bring back to life…
Sounds so easy, too…
Thanks @Koipond!
14 Likes
Thanks for the info on alcohol inks, but I do have some PP and wonder what would be a good use for it. I think so far there has been those lacy bowls you cut out and heat up to form a bowl…what else? Go 
- Rich
2 Likes
Lampshades or something like? (Although with incandescents you might have to worry about creep – I have a PP cutting board that’s about 25 years old and keeps getting new bulges on the sides as bubbles from manufacturing work their way out)
1 Like
Really? I’ve never heard that before…interesting. - Rich
1 Like