PVC heat stretching (make arms bigger/smoother etc.)

Aerial · Post by **Aerial** » Fri Jul 28, 2006 10:47 pm

I mainly apply latex for meditation (see my site) and dont work much
with PVC inflatables (they transmit vibrations poorly and the
phthalate is fairly toxic).

But I just experimented with modifying some inflatable PVC alien
figures using a hairdryer and found out something interesting. With
the air beam of a hot hairdryer you can locally stretch the
thermoplastic PVC well without risk of tearing or overinflating the
rest. The basic skills correspond to elastAyama (pre-stretching latex
inflatables), but with the PVC figures you can especially easily get
the ugly wrinkles out of limbs without overinflating the body. By
rolling up the doll body (held by body weight) and only gradually
inflating a limb, you can also e.g. sculpture the arm shape nicely
with the hairdryer. Thus to add more arm muscles, heat the shoulder
area, let it expand, then heat the upper arm, let it expand, and then
heat a section in the middle of the arm. Important is to keep an
unexpanded section between both to make it look more realistic. The
modified arms will also later stay almost wrinkle free when the doll
is inflated already at low pressure. The modified sections will also
feel nicely soft and this does likely also reduce the tension on the
seams, which prevents them from accidental bursting.

I used a hairdryer with nozzle set to full power. But regard not to
overheat a spot, because otherwise it can melt small holes or thin
bubbles into the PVC skin (popping a seam is rather unlikely, however
PVC repair glue melts easily when heated). Also be carefull with
stretching doll feet; by geometry they usually look worse afterward. I
also recommend apply heat better in a well ventilated room to avoid
inhaling too much phthalate.

With various small inflatable aliens I also expanded their
(ridiculously small) chest this way to about 150% width (pulling arms
sideways while heating chest and back, sitting on the rest) and I
reduced the head wrinkles a lot. Now the magenta coloured alien look
much more lifelike and like tightly inflated even with little
pressure. And his body even feels softer and more skin-like (about
like thin inflated viny gloves). Only my big blue alien made trouble
because the glue of many repair spots melted. But I got his extremely
skinny arms expand to about the width of my own arms.

This process could certainly also be used to smoothen or re-scuplture
PVC lovedolls or superhero inflatables. The softening of the
stretched material certainly also reduces the stress on the seams.

pupp3tmast3r2003 · Post by **pupp3tmast3r2003** » Mon Aug 14, 2006 2:41 pm

do u think i can use this hairdryer method to get the ugly wrinkles out of my HVG? She is a foam doll with a latex skin, sadly she got many wrinkles on some places

Aerial · Post by **Aerial** » Mon Aug 14, 2006 11:16 pm

pupp3tmast3r2003 wrote:do u think i can use this hairdryer method to get the ugly wrinkles out of my HVG? She is a foam doll with a latex skin, sadly she got many wrinkles on some places

No, with latex it can not help at all (because it is no thermoplastic) unless the wrinkles came from overstretching/ overinflation, where mild heat can help it to contract again. But when overheated, latex will permanently transform into a kind of sticky chewing gum rather than melting and solidifying, thus always be careful.

PVC alien overinflation

I ordered on eBay now 5 fullsize inflatable PVC aliens (140cm high) and modified 2 of them (1 green, 1 magenta) by heat stretching with quite spectacular results. I gave their skinny arms more muscles and managed to expand the tiny chest of a magenta one to almost 3 times its initial width (looking like Mr.Blowup in his inflated red latex trance suit) without damage. His chest is now wider than the oversized head and the process also turned his skin much more transparent. (I am not sure if he would possibly even float when filled with helium, but I doubt; these aliens at least weight about 260g each.)

Important for heat stretching is not to heat a spot to long to avoid melting, but welded seams react way less vulnerable on heat stretching than on ordinary overinflation. The PVC also will shrink a little again when re-heated without applying air pressure (which makes the sculpturing of arm muscles more difficult), but after severe expansion it will shrink by magnitudes less than latex. And unlike stretched latex kept in 2nd or 3rd operation range (like balloons) it also will not rapidly die of exhaustion, which makes heat-stretched PVC suitable for long term inflation (although I wouldn't want to keep inflated PVC in my appartment due to its toxic phthalate fumes), which may be also interesting for artists and some looners. Despite PVC likely stretches less than latex, e.g. for projects like LWEP the shape of a PVC inflatable can be easily modified to stay permanently expanded quite large without risk of bursting.

http://dollforum.com/forum/viewtopic.php?f=7&t=10538

Aerial · Post by **Aerial** » Tue Aug 15, 2006 5:28 pm

I today managed to overinflate a cut-out chamber of a clear blue Free & Easy PVC swim bracelet by heat stretching to really huge size. (I made photos of it.)

It grew bigger than my bodys chest without bursting, and like a latex balloon it turned very transparent and so lightweight that it sways in the air for a second when thrown upward (despite the solid PVC nozzle); it surely would float when filled with helium. It even stayed halfway rectangular at the corners after stretching them carefully. After deflation the permanently stretched foil turns quite wrinkled and tends to stick together, but it still can be re-inflated.

The first chamber unfortunately bursted because I pumped too fast. It seems to be crucial to avoid too high pressure and let the heat do its job, which takes some time. The hair dryer should not be held too close too the foil to prevent melting; between 10 and 30cm seem to be best, but the thermostat in the hair dryer also seems to turn down the heat after a while (especially when blowing too close), thus switching the dryer temporary to cold air mode helps to cool down the heat sensor to enable full heat again.

Aerial · Post by **Aerial** » Wed Dec 19, 2007 3:27 am

I have now uploaded plenty of pictures about heat-stretching to my gallery.

Watch e.g. this pretty muscle man:

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This you can do with PVC aliens:

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Or how about this big and pretty lady... :

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Aerial · Post by **Aerial** » Thu Mar 13, 2008 9:14 pm

http://www.dollalbum.com/dollgallery/in ... ?cat=10722

I have now added many new photos of Muscle Gavin to my Doll Album. It especially shows his new amazing nape muscles and translucency with daylight.

I also made a new folder with heat-stretched male superhero figures (Batman and Spider-Man), partly with nice transparent muscles.

=>

FJ_PH_maniac · Post by **FJ_PH_maniac** » Sun Jun 28, 2015 10:27 am

I just wanna say thanks to Aerial here, as well as BillNye.

I took the plunge and decided to heat stretch my Patty Penetrator and Big Bust Babe, to have bigger boobs and butt. Essentially made them bbws, but more to my preference

( niki minaj* style).

I stumbled across another method though... I use a heat-sealing iron much like this one. it has a control thermostat, so I can regulate the heaheat. It allows for very precise spot heating, which is also more risky... I could get very nice and tight butt shapes out..( like nina hartley's) but you would see stress spots and wrinkles..

Here's the hobby heat sealing iron

: index.jpg (3.28 KiB) Viewed 4766 times

Killed my lovery Modified Patty Penetrator!!

... left her in the room under sunlight and she blow at the waist seam... Really liked her newer, more voluptuous plus measurements... (

If anyone could just help me... I could share photos of the BBW'd, slim waist big bust babe.. lol I can't get myself registered on the dollablum... and I dont see a file attachment interface on the reply page...

Aerial · Post by **Aerial** » Sun Jun 28, 2015 7:29 pm

During heatstretching you must control the pressure. Better use local manual manipulation than sheer overinflation by pump or body weight. Try to install a mbar manometer (or cheap barometer built into a sealed plastic box or jam jar) between the airpump hose. Depending on the diameter of the inflated area, you normally won't need more than something like 30 mbar. Work with heat, not pressure.

I never tried a tool with hot surface like your iron (I fear it may stick and melt through) but only a hairdryer (3 speeds, 3 temperatures) with "cold air" trigger button to quickly toggle between hot and cold. I guess with a similar amount of sophisticated training one could shape PVC foil with the same skill like Venetian glass blowers do with glass art. But the thing is not perfect (to broad air jet for detail work), so I also tested a hot air soldering station (can heat very small areas with slow air speed), which however tends to output too much heat (always rises to 250°C before it falls to the selected temperature). Possibly a dimable small infrared spotlight with adjustable aperture or even some kind of broad laser would work best.

By the way, years ago in this forum someone feared that heatstretching would dry out the plasticizer and rapidly make PVC foil brittle and crack over time. I yet found no signs of such decomposition despite my Muscle Gavin figure is exposed to bathroom air and ambient light since 9 years now. He got various small damages (internal foil tore at shoulder seam, glue spots and nozzle rim broke, possibly fine leaks by wall tile scratches) but his skin still feels soft as it should. He also doesn't permanently shrink excessively when left uninflated for a while. So heatstretching at reasonable temperatures is unlikely to cause long term harm to vinyl (other than making it thinner and so more sensitive to body weight).

FJ_PH_maniac · Post by **FJ_PH_maniac** » Mon Jun 29, 2015 9:12 am

That's good news for me, Aerial! because it might be hard for me to order and get stores to ship dolls in. I want a Fatty Patty or Granny doll.

I dont really get what you mean by local manipulation though....

I basically just focus fist on the centre of the part /shape where i want it to protrode the most, quickly heat it up and then start heating around it. I dont have a cool air option on my hair dryer, but for now I'm using a can of compress air to quickly jet out blasts of cool air!.

the hair dryer is not as effective for making heels at the bottom of the the feet, like the heat seal iron does... But the heat seal iron really stresses and thins things out the areas it contacts directly. I have to mention I'm using it more effectively on the recent Calexotics dolls, which feel like they use thicker vinyl...

I do prefer the feel of the stretched doll over when I first received them...

Aerial · Post by **Aerial** » Mon Jun 29, 2015 9:50 pm

Have you tried to put a thin layer of something soft and nonmetallic with low heat capacity (paper, cardboard, felt etc.) between PVC foil and the iron? It would cool down faster than the iron itself and may make the response of the plastic less aggressive than by direct iron contact.

A hairdryer with "cool" trigger button helps much. (Sorry for error - mine has only 2, not 3 speeds, the 3rd is off.) You can use the detachable nozzle to concentrate heat on a smaller area. Usually hairdryers are not designed to run with nozzle at full heat. The bimetal overheat sensor will turn motor off for 5 minutes when switched off directly after this (and may damage it when repeated). So remove the nozzle and run at low heat for a while before powering off. With "cool" button I can easily cool the motor down for 20 seconds to prevent emergency shutdown.

For expanding large areas, move the hairdryer in circular motion rather than blowing in the center. Stay longer at the edges of an area to sculpt a flatter surface; keep air pump pressure low when working on large areas. Expansion by pressure instead of heat tends to become uneven and reshrink too much. Beware if PVC foil suddenly turns slightly hazy or greyish - then it has reached maximum expansion (3rd range operation, if that applies to plastic) and will burst if stretched any further, so reduce air pressure and let it rest for a while to regenerate. For delicate work wear an LED headlamp to see what you are doing.

FJ_PH_maniac · Post by **FJ_PH_maniac** » Tue Jun 30, 2015 12:55 am

Exactly what I realised about the pvc turning greyish. I have quite a few patches especially where I placed the heat seal iron for over 2-3 seconds. In comparison, I find using the iron promoted more even stretching.

And thanks for suggesting the headlamp. I had a lot of problems with lighting, because I was trying to be as symmetrical in the expansion of left and right body parts and it got a bit hard to compare curvatures of the surfaces.

One more thought, Aerial. in what you have tried, has it been possible to introduce a pear shaped bottom? I find it hard to do with the hair dryer, than compared to the heat seal iron.

Aerial · Post by **Aerial** » Tue Jun 30, 2015 10:36 pm

Do you talk about butt shape? I do not care about female butts - more about muscular (superhero type) males and such things, which how ever IMO is even more difficult than females since it involves many angular (non-round) shapes. A butt crack can not be simulated without internal modifications (see inflatable mannequin page for technical explanation).

The only time I experimented with an iron was a cheap steam iron (the household type for ironing laundry). I tried to re-weld leaky PVC seams but it rather stuck to the iron once it got hot enough. If I remember well, an electric hair straightener did not really work better, so I used solvent based soft PVC glue.

FJ_PH_maniac · Post by **FJ_PH_maniac** » Tue Jul 07, 2015 11:36 am

As mentioned. here are the pics.

I found a way to meld both the use of the sealing iron and hair dryer together. I find that for accentuating curves, the sealing iron is a must. The hair dryer helps in keeping expansion more even at spread area.