UPDATED with answered questions, 07/20/20 I loved Shrinky Dinks® as a kid. I love Shrinky Dinks® as a parent.
I was thrilled to see them make a reappearance on store shelves during a recent birthday party stock-pile trip. I snagged some for The Princess Cupcake at Toys R Us for what I now consider to be an obscene amount of money. That’s the upcharge for a licensed Disney Princess print I suppose. The package had six measly little images on miniature plastic chips of Cinderella and Snow White and company accompanied by the shortest colored pencils you’ve ever thought possible.
A 3 year old will blast through coloring this package in approximately 38 seconds a piece of plastic and then be ready to shrink them in the oven. In case you’re wondering, that’s about 4 cents per second.
Good stuff.
Then I started thinking… isn’t there somewhere we can buy plain sheets of Shrinky Dinks® material? Like Staples??? I dunno. Maybe, I couldn’t find any online, but what I did find were several tutorials on how to make your own Shrinky Dinks® at home.
Even better.
All the tutorials I read said that the best plastic to use is recyclable #6 plastic containers. And to use the whole thing. How do you tell if it’s the right container? Flip it over and look for the small embossed triangle of arrows on the bottom. If it has a 6 in it, you’re good to go.
So naturally, as I do, I then became obsessed about finding a restaurant take out that used #6 plastic containers and Panera quickly became my muse. After three lunch trips I was beginning to see that not only was I getting fatter, my ROI was falling far less than the store-bought Disney Shrinky Dinks®. And yes, I asked Panera for extra boxes at drive-through visit. (This was always met with strange looks from the employees)
None-the-less, I had a handful of containers to test run.
Against my better judgment, I got out the oh-so-permanent Sharpie markers and let the Cupcake draw to her artist’s heart’s content.
Once complete, we put them – square container and all — one at a time into a preheated to 375 degree toaster oven and watched them automagically shrink to a fraction of their previous size in a matter of 30 seconds or so. If you try this at home, be sure to leave the box in until it completely finishes twisting and scrunching around and lays flat.
****VERY IMPORTANT**** be sure to put parchment paper or non-stick aluminum on your baking sheet before you put your #6 plastic on it. If the #6 plastic sticks to it, you may not be able to use your baking sheet for food again.
Admittedly, we had less than stellar results the first time around. I have determined that it was because the oven was not fully preheated (our toaster oven doesn’t tell us when it’s at the programmed temp). The longer we left the oven on, the better the shrinking turned out.
Note that if your oven isn’t hot enough, they won’t shrink to a flat square.
The very last Shrinky Dink we did shrunk perfectly, but in my excitement I realized that I didn’t wipe all the crumbs out of the container first and they were like little freckles in the finished piece. Head smack. Argh.
So now that we had our Shrinky Dink mojo on – I was completely out of my Panera stash — I got desperate and tried shrinking another plastic box that I saved from the Daddy Daughter Dance corsage.
Do not do this. It did not turn out well.
Frustrated but not deterred by our original results, I went to Sam’s Club that weekend and purchased a bag of 125 #6 take out containers. They were much larger than I was getting at Panera. We tried a shrinking a couple of the boxes whole and we were again disappointed. They were just too ruffled.
So THEN I used my brain and we cut out a sheet from each side of the box (giving me now 250 sheets! WOOT! I do love a bargain) and shrunk those with absolute perfection.
The Cupcake has been shrinking for the past two nights and has the ROYGBIV Sharpie stains on her hands to prove it. My cost for those sheets is about 12 cents PER homemade Shrinky Dink now so she can plaster her room with them as far as I’m concerned.
I even started punching a hole in them before shrinking. I am thinking of making jewelry with her artwork, suncatchers, making Christmas ornaments, and… the possiblities are endless.
My apologies, I don’t have a good video of the shrinking process. I tried. Really, I did. The reflection on the oven made a great video of me and the Cupcake staring intently at it but falls short of riveting or educational viewing as you can’t see what’s happening inside at all. I’ll try again, promise.
Even though we broke the code on our DIY Shrinky Dinks®, I was still curious as to why #6 plastic works best. I sought out the wisdom of a Shrinky Dink expert to find out why. The one who first introduced me to Shrinky Dinks® a very. long. time. ago.
My dad. The chemical engineer. And he hearts polymers.
I asked Dad to explain the science behind plastic shrinkage to me. I have edited the below to remove all polymer-speak – hopefully appropriately – to appeal to the regular moms, and not just the previous engineering student moms, so you and I can also benefit from Shrinky Dinks® 101. This public service message is also provided in hopes of deterring you from melting all the plastic boxes you have in your home like I did.
So Dad, what up with the #6 plastic for DIY Shrinky Dinks®? Why does that work so well and what else can I shrink at home?
Good question about “Shrinky Dinks®”. Plastics code 6 is Polystyrene (PS) and it is the material of the “Shrinky Dinks®” and the containers you used.
To form the original PS containers you used, they were “thermoformed,” in other words, they started out as sheet, sometimes flat sometimes somewhat shaped, then heated during processing at a similar temperature to what you used in the oven. Then while hot, they were pressed into the container shape. Next they were cooled rapidly while still box shaped in order to prevent distortion from the take out container form.
When you put the take out containers in the oven, you allowed them to relax to about their original shape – and that includes shrinking since they were stretched in the original forming of the box. If you have the oven too hot then they will not shrink as evenly because different parts of the shape are different temperatures and relax at different rates. (Hmmm, so maybe my oven was too hot instead of too cold?)
The different codes on the bottom of your recycled containers indicate different basic polymers with different properties:
- Code 1 is Polyethylene Terephthalate (PET) from which most soft drink and water bottles are made and also is the material of polyester fabrics and mylar® sheets. You need a higher temperature for PET since its softening temperature is higher.
- Code 2 is high density Polyethylene (HDPE) that is fairly crystalline and melts unevenly and needs a slightly higher temperature than PS.
- Code 3 is polyvinyl chloride (PVC) and although it is glassy and could deform like PS it should be avoided due to the possible Chlorine compound that can be generated if the temperature is too high.
- Code 4 is low density Polyethylene (LDPE) and has a lower softening temperature than HDPE and near PS. LDPE still will melt and deform unevenly.
- Code 5 is Polypropylene (PP) and like Polyethylene is fairly crystalline and PP softens at a higher temperature than HDPE, so may be used in the dishwasher without too much trouble but again will deform unevenly when heated above its softening point.
- Code 6 is Polystyrene – The ONLY plastic that should be used! This plastic is usually well-marked so if you don’t see the triangle with the 6 in it, don’t risk it.
- Code 7 is for other polymers, i.e. a catch-all category, and should be avoided for “Shrinky Dinks®” since the composition and potential problems are not known and the specific properties are not given for this general category. Excessive temperatures where the material starts to smoke or odors are given off should be avoided for any of these materials.
I also asked Dad if I could fix some of the Shrinky Dinks® that were ruffled and stuck together by reheating? Or ??
Trying to fix samples that shrunk unevenly is difficult since they become tacky (sticky) when hot and would stick to an iron’s surface. If you must try to reshape them, try redoing the heating at a lower temperature. If that does not work then place them between Teflon® coated sheets with the Teflon® sides contacting the sample and a hot iron on a non-coated surface, but even that would not be very successful. Putting them in the oven between Teflon® sheet with a weight on the top could work. Reshaping with the Teflon® sheets exposes the users to many burn hazards and is not recommended.
Right. Since I have no “Teflon” sheets at home (Dad, seriously. Do you? That sounds like something you have in your lab, can I have some for Christmas???) I think those mistakes are just getting trashed.
UPDATED 07/20/20 – Another question for Dad: Why do some of the take-out containers turn white when they heat up?
As we discussed the #6 plastic is polystyrene. With regard to why some polystyrene pieces become clear when heated and others turn white is related to both the heating profile and the additive content of the piece. Almost all plastics have a small percent of additives included to improve properties for different applications. Turning white after heating is because the more volatile components become gaseous and form small voids in the material and therefore scatter light, causing whitening. A related example is a foamed styrene cup (often called “styrofoam” cup). This cup is white since the polystyrene had an intention volatile additive and the material was heated in controlled fashion during forming Into the cup shape.
Would heating at a lower temperature keep it from turning white?
Slower heating and a lower temperature for a longer time would lessen the whitening but some pieces may have too much of the additives that lead to void formation.
Thanks Dad! 🙂
I’ve got about 225 more sheets to use – what do you think we could make with them? I’d love to hear your ideas!
Ask Dad
A girl always needs her Dad, right? My retired professor of chemical engineering father is super helpful and explains things we all have questions for. There are quite a few posts where he weighs in. Look for his cute photo for sciencey insight from Dr. John!
See more Ask Dad posts:
DIY Shrinky Dinks
How to Make Fake Water
How to Make Colored Wooden Bead Garlands
What is in Piggy Polish and is it really safe?
The Science Behind Baking Soda & Paint Textured Clay Effect
May be a bit late now lol but wish sells shink sheets you can put straight in the printer.
That’s a great tip! Thanks!
Hi, can we use transparency films from projectors? Ifound a lot in our attic womdered if they could be reused.
I’m not sure – I don’t know that it’s thick enough. I would think it would curl too easily. You might try looking up what it’s made of to make sure it’s not toxic too.
I was wondering the same thing about projector film too! From my searches, most overhead projector film is cellulose acetate (plant based) plastic. #6 plastic is made from polystyrene, which is a petroleum product. So they definitely are not the same. Whether it works or not, I haven’t tried, but if it does let me know!
ps. love how your dad is a polymer enthusiast XD
Thanks for the great info! Post was made in 2015 and it is now 2018 so not sure how old your daughter is now? Six? A good project to use shrink plastic for is Barbie doll plates. Original size is around 3.5” shrinks to 1.5”
That’s a GREAT idea! She’d love to make those. I’ll tell her about it. Thank you!
We have plans for father’s day to make fish and link them together to make a keychain of “caught fish”. Add a clip and voila.
Thanks for your post! I remembered doing this as a kid and wanted to do it again for my son’s birthday party and couldn’t remember if it was #5 or #6 plastic. I’m not notified at the sharpie idea. In my memory, we roughed one side of the plastic up with sandpaper and then used colored pencils. The sandpaper gave the pencils something to stick to yielding brighter colors. I’m going to try both ways now!
That’s a great idea and now that you mention it, I think I remember that too. I may have to go back and try that as well!
Hoping you (or your dad) might be able to answer this one. I got a disposable rain poncho from Niagara Falls that I was wondering if I could cut out the logo and shrink down for a Christmas ornament. I can’t seem to find out what type of plastic is used in these ponchos or if my idea will work. Can you help?
Uh, I’m going to say no on that one. He’s out of the country currently, but I can ask him when he returns. If I were you though, I’d put the plastic over the logo and trace it and then shrink it. I’d be afraid I would ruin it otherwise!
Okay, thanks. I would be interested in what your dad has to say though…
A really fun use for shrinky dinks with older kids is to make the oh so trendy buttons and pins, things that you see on sites like tumblr. This is super easy to do, simply by hot gluing either old pins, or safety pins onto the back surfaces.
Great idea! I plan on making more this summer.
Hello! I was looking to do some shrinky dink handprint key chairs for Mother’s Day. I have 23 4-5 year olds in my preschool class. Thank you for the great info. Will let you know how they turn out.
Key chains!
Awesome! I’d love to hear about it or see photos!
Everyone please research the dangers of heating #6 plastic! Everything I’ve read and seen on the subject recommends avoiding; normally in bold red lettering. Most recycling plants won’t take it and there are recycle bands on it in some states. Don’t just take my word for it, contact your local recycling center or research it online.
Thank u so much for the recycling lable clarification! That answers a lot about why me using the plastic sheets from the bookstore did NOT work! Lol!
Seriously that thing bubbled and blackened and…. fried itself lol!
I’ll start looking for number 6 now. I’m planning to use them to diy some game tokens for my roleplaying games xD
I baked mine on parchment paper and they came out fine. The only thing I noticed is that it left a foggy film on the back. Does anyone know how to take this off? Or what else can I use instead of parchment paper to avoid getting those odd stains.
You could make book marks out of them as well
I love your post and all the comments. And please thank your dad for me too! It’s awesome that he is willing to help us with our craft projects. The cookies my husband likes come in a number one code clear plastic with the letters PETE on it. They turn white as they heat and the pieces curl up on me. The smaller ones worse than the larger ones. I’ve only done this twice. Short of trying a bunch of different temps, does your dad know the temp for PETE plastic? I’d send you a picture but I don’t know how to attach it here. Thank you.
PETE is the same as #1 plastic. Does that help? If not, I can ask him.
I have tried to make these so many times and they never flatten out 🙁
Have you tried different sizes?
Could I use acrylic paint on them and they work the same?
I think your paint will flake off during the heating process. You could paint them after they are baked though!
Rather than flaking, i’d be afraid of the paint itself blackening as it’s probably flammable material
Thank you for your detailed and informative post.???
Thanks so much for this post! I was looking everywhere on the net for WHY we can only use #6, and now I know thanks to your (I’m sure) very trustworthy Dad. Thank him for me too!
I will!!! He’ll be happy to hear. 😉
FAN FREAKI’N TASTIC!!!! Your dad is cool. Kudos for enlightening us and saving us all from inhalation of dangerous stuff.
My plastic “fetish” led me to finding reuses for every single piece of plastic headed for the trash bin/landfill.
I use a lot of clear packaging plastic. I cut up pieces to wrap my embroidery floss on. I spin fiber, so use 3″ x 4″ pieces to hold samples, sharpies, or tape makes labeling easy. My husband installed windshield wiper blades, giving me 4 extra long pieces. I made shallow drawer dividers for my plastic mini chests. Cigar boxes need dividers too, I’ve been using waste vacuum shaped packaging for cigar box organizers. Using a piece with a long rounded trough shape, I made a bobbin box.
For a fancy necklace presentation I glued velvet fabric to some vacuum formed plastic in a round shape, like a neck. You could make jewelry display and photo props also.
Yogurt containers get drain holes and start all my seeds,
I’d love to know: which categories of plastics tend to hold up over time better? Which ones are faster to degrade? Which glues work well for each category?
Try restaurant supply stores- ours is called Cash & Carry” for mass quantities of anything. (not certain #6 avail there, but likely lots cheaper than retail.
Wow, you’re legit! I’m not sure about the answer to your question but I’ll ask him. 🙂
Rebecca, yeah, I’m quite late getting this information, but regarding your questions… I was a recycling specialist in California for nearly a decade, and in dealing with all of the different materials that can be re ycled you learn some stuff. You ask which degrades fastest? That would be #2 plastic, like milk cartons. They can deteriorate in sunlight in less than a month. Next would be your #5 and #6, when left in their original stretched shapes. They are a form of styrofoam and are just as fragile if not released from the shape they’re manufactured into. Once you melt them down to any other shape, where the elastic effect is no longer working against it, it can last years and years. Number 4 really wasn’t recyclable, so we rarely saw any, but the pet (#1) seemed to depend on the shape, size , and manufacturer for the longevity of the plastic… Brand name sodas generally held up to almost anything and could be used for years, but some had some kind of oil in their plastic that would leech out into whatever you held in the container, so I personally never recommended that. But for plastic strawberry boxes or other non-liquid containers,re-use and repurpose to your hearts content. I make appliances for my daughter’s (and now granddaughters) fashion dolls and dollhouse furniture. I also make extras to provide at Christmas, along with the dolls, for local kids who won’t have much. It keeps the landfill empty and makes faces light up, which is usually all I want for Christmas anyway ?.
Happy recycling!
I’m wanting to make my own for scrap booking! I’m just not finding the cute sticker type designs I’m really looking for so I plan to make my own out of shrinky dink material. Thank you for the very thorough post it was exactly what I was looking for!
Awesome! I’d love to see how it turns out!
Can you color on the ink jet sheets?
Ink jet sheets? I’m not sure I follow?
Will this work if you cut it into a different shape at the beginning? Like a circle or even a dog shape or does this have to be a square?
I’d try it but don’t cut it too small as it may curl as you heat it.
I haven’t done any shrinks dinks but I have plans, your information is so beneficial for some us starters especially one like me that likes to pay less for everything that comes in front of me. I love making crafts and sewing from scraps. From now on I will be looking at every containers to find that #6, thanks a million.
Great! Good luck! 🙂
i know i am a little late to the party, but does white #6 plastic work? thats what my yogurt comes in and it seems like a shame to waste! 🙂
If it’s #6, it SHOULD work! Try it and let me know!
Does the colour rub off at all? Would you need to coat them with modgepodge or some sort of sealant to prevent it from coming off?
The color has not come off of ours at all.
I used a calligraphy pen once that was not permanent and it did come off. Stick to the permanent markers.
You can use colored pencils as well! I have done it as a class project. I believe somewhere someone told me or I read to use the brand which I cannot remember, but begins with the letter P! Anyway, color hard for lasting bright colors!
Hi!! Can I use acetate instead of #6 plastic?
It might depend on your oven. According to Dad, acetate softens at 405 F and that is a little above the limit of a standard oven, whereas polystyrene softens below 200. Good luck!
Love your post! Can you please find a way to use #1 plastic? It is such a shame to throw out so much plastic. Is is safe from a toxic standpoint, but just not as uniform in results? I’d love to make masses of buttons if you and your dad can figure a way to melt it.
Hi Deb, I went to Dad for the answer to this. Here’s what he said — verbatim — Plastic listed as #1 is Polyethylene terephthalate, commonly called PET. Often bottled water and other liquids are sold in PET bottles. The melting point of PET is somewhat dependent upon what else may be compounded in it but for normal PET the melting point is 260 C i.e. 500 F. That is the temperature normally reached in an oven when broiling and the highest temperature that a common oven can be set. However before any plastic melts it soften and can be carefully shaped as it is in forming the bottles etc. If I were to make buttons from it as the questioner asks, I would first form a sheet of it by putting it in the oven on a proper support such as metal, not teflon, with a weight on it to force it to form a sheet first rather than just ball up. Please note that teflon and other non-stick plastics will degrade at this temperature and give off noxious fumes. After cooling use a punch to form the button shape then reheat to a lower temperature while watching to see it blunt the edges but not shrink too much. It will take some practice to get the size needed since it will always want to shrink some. I have not tried it but think this might work. If the PET sticks to the support or weight the user might try quenching the entire material, support, weight and plastic by quickly putting in water.
GOOD LUCK! Let me know if you try it and it works!
Thanks so much! I’m going to go buy a cheap toaster oven to combat “noxious fumes” and do it on the deck. I’ll let you know if it is a disaster or mild success!
At walmart I found clear plastic plates that were #6 10″ diameter.
That’s AWESOME! Much better than stocking up like a restaurant at Sam’s. Thanks for sharing. 🙂
Thanks for the tip!
I use the material from meat products. Washed off of course.
Very fun post….and I loved the science behind everything!
Alas, I only have #1 at home currently. But I’m going to keep my eyes out at Sam’s!
Hi Wren,
Trust me…. Sam’s is the mother-load. Stock up for those winter days when you can’t go outside!
*motherlode
Hi
It seems there’s a special Shrinky Dink that you can put in a laser printer and print out your own pictures – for those of us who aren’t any good at drawing. Does anyone know if it’ll work on takeout containers?
Thanks 🙂
Just trace images 1st then cut out.
Thank you so much for this information. I’ve seen some bloggers heat up plastic and transform this into jewelry pieces. Do you know whether this is dangerous – ie toxic fumes? Or just avoid the ones where you have marked in bold “avoid” 🙂 Thanks again for sharing!!
Hi there! If it were me, I would ONLY use #6. I think that’s the only way be confident you’ll avoid toxic elements and poor results. Good luck! Send me some photos of your work, I’ll feature them on the site. 🙂
Thanks so much for the info. Will try something out and hopefully it will work!!! Have a great weekend. 🙂
Important– you listed Polypropylene as Code 6 but it’s Code 5 (the one you thought your dad missed). Polystyrene (PS) is Code 6, and the only plastic that should be used. Sometimes Code 1 containers look the same (clear, thin, somewhat brittle), but usually Code 6 is well marked. An image of the code may be a good idea.
Although you have it right elsewhere, if someone just lifted the list, they may use the wrong thing.
Best regards,
Kris Atkinson (protein chemist)
Thanks so much for helping me with that! I’ve updated the post. 🙂