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Old 09-06-2021, 04:32 PM
Merl Merl is offline
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Default Replasticizing hop balls
Idea credit goes to @Unicks.

The goal is to see how much size increase I can get from an original Sun Hoppity Hop using acetyl tributyl citrate, a PVC plasticizer. The HH was made of thick PVC compared current cheaper, thinner hoppers so I ordered a large bottle to ensure I has enough.

The HH is max rated at 20" for teens and adults, per original instruction sheet. Last year, I manage to heat stretch an un-replasticized HH to right at 24". This was the absolute max and didn't leave very much bounce.

The current HH has been coated inside and out with ATBC, which the vinyl immediately soaked up as it vanished within a few minutes. The ball is now hanging in a closet under some pressure. It will be measured daily for any change in size and softness.

Did the same to a new Hop! 66, which is of a different material and presumably not lacking in its original plasticizer. The maximum rated size is 26 inches. After coating the inside yesterday with ATBC and inflating, it is now near 28 in. but still somewhat bouncy. This may still be within the factory range of inflation so will keep watching.

Unicks said it took about a week to see a real difference. End result for the HH and 66 is to see how much relaxation of the vinyl happens chemically leading to an increase in size, which then may or may not be followed up with heat stretching of the HH.

Last edited by Merl; 09-06-2021 at 05:43 PM.
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Old 10-06-2021, 01:49 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
HH: up to 20.3" diameter from 19.8 yesterday with no added inflation.
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Old 12-06-2021, 04:08 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
21.5" after another dose of ATBC late yesterday, a hot soak today to speed things up, and a top-off of air. No distortion and still flexy enough for comfortable use; firm but not rock hard. Bounces me a good 18" high....the cheap softer vinyl ones would have trouble doing that even fully inflated.

Last edited by Merl; 12-06-2021 at 04:12 PM.
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Old 13-06-2021, 06:56 PM
Yen_D_Heart Yen_D_Heart is offline
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Default Re: Replasticizing hop balls
That sounds really interesting!

Can you explain how you did that? Do you have a step-by-step guide or general tips that you could share?
I have a 32" hopper that I haven't inflated ever. I would love to have bigger hoppers than that, so maybe it's worth a shot?
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Old 13-06-2021, 10:06 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
If you have ACTB, first step will be to thoroughly coat the entire inside, inflate it, thrn watch for any change as it soaks in.
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Old 15-06-2021, 03:44 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
Some air was let out the other day after the top off but the ball is again at 21.5 (about same as a Hop! 55) but perhaps a bit bouncier than before. It's going to take some time to really see results from the ATBC.
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Old 17-06-2021, 08:52 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
Haven't been too confident in the ATBC that came from China, so last week I ordered the softener from Sculpey (it's back in stock). It arrived today. Deflated the ball and dosed it with a 1 oz bottle of Sculpey's ATBC. Rubbed it in thoroughly and reinflated three hours ago. The ball is holding at 21.5 but is definitely not as firm as it was at the same size yesterday (remember that this is 53 year old vinyl already 1.5" above rated max...it SHOULD be tight as a drum). Maybe now we're starting to get somewhere.

Last edited by Merl; 17-06-2021 at 08:57 PM.
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Old 18-06-2021, 01:45 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
21.97" and still has decent bounce.

Last edited by Merl; 18-06-2021 at 01:52 PM.
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Old 19-06-2021, 08:12 PM
Merl Merl is offline
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Default Re: Replasticizing hop balls
22.5" after leaving inflated in the sun inside of a black contractor bag. Still bouncy enough.
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Old 22-06-2021, 12:38 AM
Unicks Unicks is offline
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Default Re: Replasticizing hop balls
@Merl For what it's worth, I've noticed that temperature cycling seems to speed up the absorption. I find that the vinyl seems softer when it's cold, then brought back to 80+F we get the soft-sticky vinyl again.

I've tried to poke a hole in the ball I have to see if the vinyl has lost it's strength or elasticity at full recommended inflation, but it remains soft and quite strong. Makes me leery when I see what ATBC does to vinyl items with pinch seams and how easily they come apart when you over do it. Maybe because these vinyl balls are seamless you can have a bit more fun with them before the pop.

Good luck!

U
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