The probability of other creatures organically dying blue

[613 mitzvot]

They milk the snails, applying them directly to the textile.

for reference:

https://www.atastefortravel.ca/2387-que ... sea-snail/

[Yitzchok Mickler]

I see from the link that you gave that the Mexicans also use sunlight to turn the yellow into purple. If it passes through blue on the way to purple, the answer to Rafi's question is 100%

[Iz1]

Mexican "Indians" dyed with juice milked from the hypobranchial glands of their local shellfish, without damaging the snails, so that they could reuse them.
We are researching how to apply this technique to banded dye-murex.

[Yitzchok Mickler]

I assume that will lower the price of Techeiles and it will be be more eco-friendly. 

[rhecht]

Sorry for the delay. They spit on the snails which causes them to secret a drop of that dye. So the snail stays alive which is a bonus.

The Halachic issue then is whether Techeiles needs to be specifically from one species of Chilazon which might invalidate anything not from the Mediterranean, or if the Chilazon species can produce blue which is the target color shade set.

[rhecht]

Mexican "Indians" dyed with juice milked from the hypobranchial glands of their local shellfish, without damaging the snails, so that they could reuse them.
We are researching how to apply this technique to banded dye-murex.

 

Beautiful! That way these snails can be reused. It's win win.

The next question then is, if the ancient dyers could have dyed by spitting on these shellfish, why was Potzea a definitive Melacha?

[Nosson]

The Medrash says that it was nignaz- this is also brought down by the Gra lehalacha.
It is not improbable that a creature went extinct and is unknown to science.

 

Please clarify.

Where is the Gra exactly?

[Mr. Genugshoin]

The Medrash says that it was nignaz- this is also brought down by the Gra lehalacha.
It is not improbable that a creature went extinct and is unknown to science.




 

Please clarify.

Where is the Gra exactly?

 

או"ח סי' ט ס"ב


 בזה"ז כו'. ע' מ"ר פ' שלח ועכשיו אין לנו אלא לבן כו': 
 
 

[Doorknob]

The answer to the original question here is that there are numerous creatures that dye blue, all from the murex family. You can see this on ptil's website.

[rhecht]

The answer to the original question here is that there are numerous creatures that dye blue, all from the murex family. You can see this on ptil's website.

 

Which one? The plicopurpura pansa was recently discovered in Mexico so that's a close candidate. The Halachic Kashrus on using that snail is something to discuss decades down the road. Right now the focus is on the trunculus as that was used in the Mediterranean area in ancient times.

I'd be very interested to know which other snails make this kind of blue (please share here). Branderis yields a pinkish-orangey purple hue set, and stratomina haemastoma yields crimson red.