I own a Canon Ivy Cliq camera. It’s basically an instant camera, and the photos it prints are also stickers. It uses Zink film, which is not photosensitive; instead, it works via “heat-sensitive crystals”.
What are your thoughts on sticking photos onto the postcard?
I have previously mailed a postcard with a photo from my camera on it, so I know it can survive the trip. (At least within the US)
Slightly off topic: thoughts on wax seals on postcards? yay/nay
I would love such, it’s very personal.
Wax seals too, yay for me 
here is also a topic showing wax seal:
I can tell you that Canon Zink photos will survive international travel on a postcard — at one point I was sending quite a few of them to my penpals from Australia to USA, Asia, and Europe! So, as you can guess, I really like the idea. I would caption the photos with whatever I could fit in the remaining space and I think it gave a really lovely result (that said, I’m also a fan of sending real instant Instax or Polaroid photos as postcards so I’m extremely biased).
I also enjoy when I occasionally get wax seals on postcards but, for me, it’s not as exciting as instant photos! 
Edited to add an example of a postcard I sent with a Zink photo attached:
Adding photos to a postcard can be a wonderful way to personalize and enhance your message. Plus, it’s a great way to share memories and experiences in a tangible way. Overall, I think it’s a fantastic idea!
How do you mail the actual polaroids? My biggest concern is the latest chemistry isn’t the best. Also, where would I put the stamps? the address?
you opened a rabbit hole I hadn’t considered. I have so many questions
It seems to me it’s a wonderful idea because personally, I would cherish such a postcard as much as possible And the wax seals are absolutely cool; they can complement the postcard’s idea and just be a beautiful touch on the card.
I put the stamps, address, and message on the back. For years I used a white paint pen, but now the paint is sticky on ones I wrote 10-15 years ago so I very recently started using white labels.
This isn’t the best photo because it was only intended for my personal reference (I take photos of all cards I send so I can make sense of the Hurray messages) but it gives you the idea:
I have sent a handful of Polaroids and honestly probably hundreds of Instax photos from at least 10 different countries, and I’ve never had one arrived damaged, surprisingly. This was my first official one, and I know it was a bit of a gamble but the recipient’s profile made me feel like this was perfect for them, and then their Hurray message was really lovely! 
Yes to wax seals on cards!
I wax seal my postcards with an initial all of the time (unless I forget or am writing in Chinese)
I even had the little wax seals premade for when I’m travelling 
I stick a bit of double sided tape on them and keep them in a tiny ziploc bag I bring when overseas
The premade seals for travelling are such a neat idea, I shall definitely adopt it 
Wax seals often arrive broken to me. They also tend to leave an oily mark on the postcard, which makes it unrecyclable in the future. For these reasons I am not a fan.
Photos, on the other hand, sound like a fun idea!
I think the photos glued on postcards can ruin the sorting machines if you do not send them in envelopes.
Thank you for the explanation that makes a lot more sense now. My other instant camera is a Polaroid 600 so the film chemistry is not as stable as Fujifilm from what I’ve researched. Also the 600/I-type film would be too small to count as a postcard.
But after reading all the comments I’m definitely going to order more Zink paper for my Cliq camera.
Can it be in those cases it’s not wax, but rather candle (stearin) what is used? I remember as a child we used normal candle, and it got broken and left the stain.
The wax that I use, you can’t take away from the card cleanly (or what I tried ), as it then tears the paper and if one wants to recycle, it’s easy to tear the wax away.
I have no idea honestly. I personally never made wax seals so I cannot tell the difference even when I see the wax seal. I just know I have received a few broken wax seals and some only greasy stains where they had been. It could be that the wrong material was used.
I think it’s a fantastic idea to stick polaroids on postcards. I would be so happy to receive one myself. You could glue and then use washi tapes on the edges so it does not fall off easily. Washi tapes would make a good picture frame too.
