Foam tree stump prop build - Part 2

Finishing off the bottom and inside, and my tips for working with this stuff.
hackaday.io/page/4899

[@allisonhodge4576]

You have saved me SOOOO much money showing how to do this! Thank you so much- Love from MN ❤️

[@theRoxiHorror]

Thanks for posting this how to sir -made a stump in one afternoon thanks to your tutorials/ lifesaver. Btw the tip about the water was fantastic ❤️

[@DarenSchwenke]

Glad I could help. Post what you did so I can check it out.

[@Outdoorlass]

Thank you, you are amazing and the tricks were helpful. I'm creating artificial trees in tall vases for a corporate business and I didn't know about the trash bag trick or the acetone trick.

[@DarenSchwenke]

Thank you. I'm glad it was useful to you.

[@geanesousaaguiarpereira4910]

Que material usa pra fazer o efeito casca no papelão?

[@monicachaves21]

Es la espuma que crea el efecto

[@begemans]

What is that youre using to help sculpt it? A regular plastic trash bag?

[@DarenSchwenke]

Yes. Polyethylene and vinyl don't stick to urethane.

[@shock_wave0114]

Great series! I know I'm a little late to the party but: I'm making a tree stump for my school's production of 'booby trap'. Where can i find the spray foam at, home depot or lowe's?

[@DarenSchwenke]

I have tried them all (that I have found), but I continue to use 'Great Stuff' in the red can. Virtually every store with a paint section will have it, including Walmart. It's about $0.50 cheaper there per can as well. There are other versions for that brand, and other brands of urethane foam as well, and they all act a little differently. The window/door formula is lower expansion, the big gaps formula is high expansion, and the generic version Walmart used to have gives a little different pore size and dispenses a little differently. I haven't seen it lately though so they may have stopped carrying it.

[@shock_wave0114]

@@DarenSchwenke thanks for the quick reply and explain what the other brands do!

[@prettybird2588]

Awesome! Resourceful imaginative hacker. I am transforming my backyard into a wildlife habitat for my squirrels chhipmunks and birdies. I want to make a tree stump water fountain. You have any advice you could give me?

[@DarenSchwenke]

Well... Don't rely on the foam to retain water. Getting it to not have holes which will leak water without a mold is a loosing battle and you won't do very well. Put some container inside it, and then coat that in foam instead. Keep in mind the plastics that you can't adhere to with urethane, or after the fact when they come apart, seal the two back together with something else like silicone caulk (which you can't paint!). Second, provide some internal structure to whatever you build outside of the foam. Here I had it easy as this was a stage prop and if it sat in the rain and lost the strength of the cardboard, that would be their own fault. For more freeform shapes, we have also used chicken wire, spray glue, and paper/plastic as the base structure. This worked *really* well and actually survived falling off the top of a car while moving it, several times... You don't want to know. Just make sure the foam also encases the wire frame directly by also coating the inside surface, and compress this foam just as soon as you can without it sticking, and you will end up with something pretty tough! The foam will degrade in sunlight, and I would not recommend cutting the foam at all if you are going to use it outside. If the pores are closed, such as when you don't cut the foam and use the outside surface as it is and then paint it, it can survive. However, I have had good results with both cut and not cut foam by using regular latex house paint, although cut foam requires 3x more coats to seal it. Good luck with your project. :)

[@prettybird2588]

@@DarenSchwenke thanks so much for answering me. 👍 it does make perfect sense what you just said. I assumed that inside was waterproof just like the outside is when it's dried. I'm going to take your advice and use the chicken wire as an armature frame, stuffed with styrofoam or newspaper to give it shape and then mold it with a hypertufa mixture. ( 1/3 peat moss, 1/3 vermiculite and 1/3 concrete mix) it turns out very lightweight and then seal it with Thompson's water seal. I was going to stick a PVC pipe in the middle so the plastic tubing can slide up the trunk. Anyways it was great to throw my thoughts out there to somebody who could MacGyver almost anything. I appreciate it thank you.

[@DarenSchwenke]

@@prettybird2588 The foam when compressed while curing *is* actually strong enough to stand on it's own, but this is kinda hard to do right and will require some trial and error to get right. It is *mostly* water proof as long as you don't cut it and can seal the surface with something like latex paint. If it is in continuous contact with water though, it will absorb it. I have tried Thompsons, acrylic enamel, polyurethane, dry wall compound, and automotive body filler for sealing and smoothing the surface here. Dry wall compound worked great for smoothing it, and then just regular latex paint worked the best as it created a definite skin, which then laid smoothly over the top of the foam. The Thompson's mostly soaked in and although it may provide protection from UV and such, it didn't really add anything to the structure. The drywall compound is probably not something you want to use for an outdoor application though. This is my personal channel, although I did have aspirations of eventually creating content which is something more polished. I have yet to achieve this, but that was the goal and I'm doing that here: kzbin.info/door/Yu_LuDhsQ62_XPZKdGtT_A