# Casting with Gorilla Tape Molds



## rocky1 (Jun 15, 2017)

Well I had several questions on this over the Black Locust hybrid bowl, and I had taken pictures before and simply hadn't got around to doing this yet, so for the benefit of those interested...

@Nubsnstubs
@chippin-in

Here's how I do it!

The molds pictured herein were set up to cast scales for @NeilYeag - dimensions he requested were not standard scale size because he's making littler knives.

I picked up a couple rolls of Gorilla Tape awhile back just to have around the shop, it's WAY TOUGHER than duct tape if you've never tried it. Imagine the best duct tape you've ever encountered on steroids, and you're maybe close. If you get stuck to it, it's really tough to get loose, seriously. Try laying a piece flat on the counter some time.

At any rate I figured my molds out and sawed up a wally world cutting board. Haven't been able to find one in even 1/2" thick, everything I've found is barely 3/8", so screwing this stuff together really didn't seem an option to me. durability of a mold over the long haul just seems real iffy with no more meat than that to screw into. Over-tightening a little is going to spread the HDPE, and strip your holes unless you use some little bitty screws, which don't work well when you have short fat fingers. Having had minor issues with leakage on a previous mold I attempted to duct tape, I decided to try the Gorilla Tape.

When stocking up, I'd picked up a roll of 1 1/2" and a roll of 4", (_actually I think it's about 3 1/2", but I'm going to call it 4_), and the 4" stuff looked like an excellent platform to build molds off of. So I took my pile of pieces and tossed them in a pile on the work bench.





Layed out a piece of the 4" Gorilla Tape long enough to run the length of the mold and up the ends. Then started piecing things together. (_Got this one a little off center, but you're going to have to live with it for the purpose of tutorial without having to take a bunch of pictures again, so imagine it centered, so it wraps up both ends. )_





I ran a piece of the 1 1/2" down each side to wrap under the bottom and seal the joint there. Cutting the corners and folding them around and over each other. If you fold it under the bottom as pictured, a quick slit down the exposed fold with the utility knife, does the job. I've found it easiest to slip this over the edge of the counter top, and the bottom piece of tape will fall just slightly out of your way for pulling the side piece around, then fold the bottom up. Otherwise they stick together to often and are a PITA.

At any rate, this double seals the end joint.





To remove the cast, I simply cut the corners over the joint in the HDPE, then using a beekeeper's hive tool, since I got one, and it is very convenient for this task, I rap the sides to break the cast lose from the mold, fold the side down so I can get under it and pry, and pop it loose from the bottom of the mold.

If it comes out clean, and I'm going to reuse the mold, I clean any little chips of resin that may be stuck in the joints out as best I can, and work the tape along the joints to stick it all down good and tight again. Then I cut small pieces of tape to reseal the cut corners, and wrap another piece around the corner, as seen right rear, to seal them back up as below.





Cast scale in mold...










Occasionally they don't cooperate when removing them, and it's necessary to tear the mold down to remove the cast piece. That is usually due to joints not fitting tightly, and resin running into the joints of the mold as pictured below. Getting the joints tight was really difficult to accomplish on these molds with all the little pieces to tape together. While they do save a little work when assembling molds, and save a little cutting board when sawing them out, it's much easier to use a single cell mold, you can tighten it up better and get away from this resin in the joints issue.











Resin in the joint does make the cast more difficult to get out of the mold, but it also causes problems with reusing the mold. Where you see the bottom corners broke off the stuff in the joint, it stayed in the joint, and it usually shatters. Again the glue on Gorilla Tape is really nasty, when stuff like this breaks in a joint, it doesn't come off the tape easily.

If it remains stuck in the joint, it prevents you from tightening your joints back up, and sticking your tape down in subsequent casts.  That in turn allows resin further under your tape, and shortens life of the taped joint.

Before it's asked:

-- No, I do not calk my joints! I tried caulking my joints, and everything I've tried to caulk them with led to soft resin in the corners where it was caulked, which in turn leads to cleaning molds more often, which I'd really rather get 10 pours out of them than 1; just sayin. Keep your joints pulled up as tight as possible and you really won't need to caulk them. 

And, that's all there is to it!

Reactions: Great Post 1 | Informative 3


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## Graybeard (Jun 16, 2017)

Great post, thanks! Appreciate it.

Reactions: Thank You! 1


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## Schroedc (Jun 16, 2017)

Great post! I've done something similar, taping the seams and clamping the mold together. As far as thicker HDPE, If you have a local restaurant supply they'll have the thicker cutting boards. I got a piece 3/4 thick, and lots of 1/2 inch available

Reactions: Thank You! 1


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## Tony (Jun 16, 2017)

Rocky, I can send you all the 1/2" plastic material you want. Got some 3/4" and 1" as well if you need. Tony

Reactions: Thank You! 1


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## kweinert (Jun 16, 2017)

Tony said:


> Rocky, I can send you all the 1/2" plastic material you want. Got some 3/4" and 1" as well if you need. Tony



I'm not real big into casting but I've got a couple of things I want to experiment with. If you have enough 1/2" to spare to make a couple of bottle stopper sized blank molds I'd gladly pay shipping (if the offer extends to anyone but Rocky, of course.)

Thanks.

Reactions: Thank You! 1


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## Tony (Jun 16, 2017)

kweinert said:


> I'm not real big into casting but I've got a couple of things I want to experiment with. If you have enough 1/2" to spare to make a couple of bottle stopper sized blank molds I'd gladly pay shipping (if the offer extends to anyone but Rocky, of course.)
> 
> Thanks.



Of course Ken. PM me your info and what sizes you need and I'll get you taken care of. Tony

Reactions: Like 1


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## rocky1 (Jun 16, 2017)

Found a site for HDPE, can order any size, and for a nominal fee they cut to specified dimensions. Also have round stock available which would be really cool for casting call blanks. Turn the HDPE to a specified taper in the barrel and specified bore for the reed.


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## rocky1 (Jun 16, 2017)

The Wally World cutting board stuff works fine in smaller molds of that nature Ken. If the sides spread a little I cut a piece of tape, apply to one side, lay it on the counter, press it good and tight and wrap the tape over the other side good and tight. Typically get it tight enough the resin won't seep into the joint if the mold pieces were sanded clean.

Reactions: Thank You! 1


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