Blue strips

Marting

Est. Contributor
Messages
253
Role
  1. Private
Hi guys. Quick question. Why do lots of ABDL nappies have that blue strip on the inside? I can't see the purpose of it. Am I being dumb?
 

PurplePup89

Est. Contributor
Messages
766
Role
  1. Diaper Lover
  2. Babyfur
  3. Diaperfur
  4. Little
Is the blue strip a different material than the rest of the diaper? I've been meaning to make a post asking about the actual build and construction of a diaper, because I'm interested in how they work on a technical level.
 

bambinod

Est. Contributor
Messages
10,372
Role
  1. Diaper Lover
Hi guys. Quick question. Why do lots of ABDL nappies have that blue strip on the inside? I can't see the purpose of it. Am I being dumb?

I suspect many years ago when the idea of "surge zones" was being heavily marketed as a feature of premium diapers, they colored the crotch area blue to indicate it had a surge zone. I don't believe a lot of the diapers WITH surge zones actually had them colored any different, it was just a color they added for marketing purposes.

Some modern adult diapers also have that blue area, but again it's just coloring, it doesn't usually even mark WHERE the surge zone is. Most surge zones aren't even rectangular. They usually have a "short thermometer" or hourglass shape to them. Hold a diaper up to the light and you can easily see where it is if it has one.

Rearz Inspire Select have the same blue rectangle as the Pampers they were made to imitate.
 
Last edited:

DiscreetDL

Est. Contributor
Messages
302
Role
  1. Diaper Lover
Its where the majority of the absorbent polymer is, if you wet standing up your pee will follow gravity to the bottom of the diaper, the front will swell but most of the SAP (super absorbent polymer) is in the center because the white fluff can only hold so much and when you really wet it will run down to the center.
 

WillFord384

Est. Contributor
Messages
238
Role
  1. Diaper Lover
Last edited:

bambinod

Est. Contributor
Messages
10,372
Role
  1. Diaper Lover
Its where the majority of the absorbent polymer is

I would disagree with that. SAP doesn't wick at all. Zero. To get a diaper to wick, there must be pulp. Pulp doesn't swell much when wet, it's job is to move the liquid around (via capillary action) to dry parts of the diaper, to spread it out evenly.

The areas around the perimiter of the diaper are where the SAP is higher. You don't want liquids to flow past those areas, because that's where the diaper ends and the leaks begin!

So the "hourglass" area you can see in many diapers where you hold them up to the light is the "surge zone" that has a lower ratio of sap to pulp, to distribute the wetness from front to back.

I'll try to get a few pics later to show you what I mean. I'll even do it with a diaper that has the painted blue rectangle in the middle, so you can see how the blue rectangle has little to do with where the surge zone is. (location, size, OR shape)
 

tiny

Est. Contributor
Messages
5,831
Role
  1. Little
I agree with @bambinod. The "blue rectangle" in diapers is... just a bit of the padding that is dyed blue.

The colours white and blue are common in medical environments. White highlights any dirt/uncleanliness. Blue contrasts well against red (blood). Also, blue is rarely found in foodstuffs, which minimises the "disgust reflex".

So... the blue colouring doesn't indicate anything special.

The same goes for multicolour toothpaste, dishwasher tablets, etc., etc. That stuff does ONE THING. The colours are just there for branding. The only difference between the coloured parts of these products is the dye.
 

bambinod

Est. Contributor
Messages
10,372
Role
  1. Diaper Lover
Here's a freshly unfolded Little for Big Baby Cuties attached to a shop light to candle it. The back (tapes) side is on the right.

surge zone.JPG
If you look closely, there are a total of three pads stacked up. There's the hourglass, then you can see the edges of a long narrow pad that stretches from left to right. (you can see it extend a bit on the left and right, square cut off) And then there's that big patch of darker yellow shaped like a rounded-end band-aid in the middle. (it looks like its getting wider in the middle, that's just the diaper distorting away from being flat due to the leg gather elastic)

surge zone annotated.JPG

I think the first layer is the orange hourglass, a medium sap mix, then over that they put down the high sap red layer to greatly increase capacity, and then last they put down that purple surge zone strip. in this case, the surge zone goes all the way from front to back, and this seems to be pretty common. In this case I think the surge strip is made from the same padding as the hourglass. On other diapers it looks different, maybe a different sap ratio. (less) But in this case it looks identical, it just doubles the thickness of the padding up the middle.

I'd wager that 80% of the capacity of that diaper is in that orange sap insert, and that it makes the crotch swell to like 5x its regular thickness when wet, where as the rest of the padding only doubles at most when wet.

Notice that blue "paint job" in the middle doesn't correspond to anything, it's entirely for looks.

I've seen a few examples of diapers where they didn't have a high-sap insert in the middle, and the surge zone got wider in the back, but was just rounded off in the front like the sap insert above is. Might have been an old Bambino design. (the current all-over-print ones I have don't do that, they look like the above)
 
Last edited:

WillFord384

Est. Contributor
Messages
238
Role
  1. Diaper Lover
Here's a freshly unfolded Little for Big Baby Cuties attached to a shop light to candle it. The back (tapes) side is on the right.

View attachment 54712
If you look closely, there are a total of three pads stacked up. There's the hourglass, then you can see the edges of a long narrow pad that stretches from left to right. (you can see it extend a bit on the left and right, square cut off) And then there's that big patch of darker yellow shaped like a rounded-end band-aid in the middle. (it looks like its getting wider in the middle, that's just the diaper distorting away from being flat due to the leg gather elastic)

View attachment 54713

I think the first layer is the orange hourglass, a medium sap mix, then over that they put down the high sap red layer to greatly increase capacity, and then last they put down that purple surge zone strip. in this case, the surge zone goes all the way from front to back, and this seems to be pretty common. In this case I think the surge strip is made from the same padding as the hourglass. On other diapers it looks different, maybe a different sap ratio. (less) But in this case it looks identical, it just doubles the thickness of the padding up the middle.

I'd wager that 80% of the capacity of that diaper is in that orange sap insert, and that it makes the crotch swell to like 5x its regular thickness when wet, where as the rest of the padding only doubles at most when wet.

Notice that blue "paint job" in the middle doesn't correspond to anything, it's entirely for looks.

I've seen a few examples of diapers where they didn't have a high-sap insert in the middle, and the surge zone got wider in the back, but was just rounded off in the front like the sap insert above is. Might have been an old Bambino design. (the current all-over-print ones I have don't do that, they look like the above)

That's a great photo. Now I feel like I need to go back and re-photograph hundreds of diapers but this time with a light table or something. I hope that was an LED shop light so you didn't have to worry about getting the shot before the diaper started melting :)

And thanks for the explanation. I had no idea of the interior structure.
 

Zeke

Est. Contributor
Messages
955
Role
  1. Diaper Lover
  2. Incontinent
Here’s a link to a YouTube video about the engineering that goes into disposable baby diapers and they use much of the same design features of adult disposables:

When I was mixing my generic Miralax, that I take to combat opioid induced constipation, I started to think that it’s polyethylene glycol, a polymer that absorbs moisture, or the juice I mix with it. I wonder how different it is from super absorbent polymer, SAP, that’s in disposable diapers? If they’re similar then I’ve been drinking a SAP mixture which, after processing, is dumped in the disposables that I’ve been wearing that contain the some of the same material that’s be deposited in them. I’ve got to quit thinking when I’m mixing that stuff up!
 
Last edited:

WillFord384

Est. Contributor
Messages
238
Role
  1. Diaper Lover
Here’s a link to a YouTube video about the engineering that goes into disposable baby diapers and they use much of the same design features of adult disposables:

When I was mixing my generic Miralax, that I take to combat opioid induced constipation, I started to think that it’s polyethylene glycol, a polymer that absorbs moisture, or the juice I mix with it. I wonder how different it is from super absorbent polymer, SAP, that’s in disposable diapers? If they’re similar then I’ve been drinking a SAP mixture which, after processing, is dumped in the disposables that I’ve been wearing that contain the some of the same material that’s be deposited in them. I’ve got to quit thinking when I’m mixing that stuff up!

Thanks. That was illuminating.
 

Zeke

Est. Contributor
Messages
955
Role
  1. Diaper Lover
  2. Incontinent
If you liked the video about the engineering behind a disposable baby diaper you may like these two about production of the baby diapers and about a new, biodegradable SAP:


 
Top