Topic: textured old glass sand or something? black glass bottle 19th century

[flying free]

can anyone tell me how the base of this bottle was formed please?
http://www.aaawt.com/web_images/Bottle,-ASCR_bottom_843-228.jpg

I can see what looks like a pontil mark but it's the texture of the inside of the base that I'm particularly interested in - that subtle grainy effect.  Were they stood on sand to anneal or something?  is that even possible?
Hope someone knows
It's third pic down on this link.

m

[bat20]

This site may help https://sha.org/bottle/bases.htm

[flying free]

Hi thanks
I've been through the site many times - it's a great site.
I just couldn't seem to find anything on this though.

m

[pamela]

  This mark was formed when the hot glass gather on the flared or ball shaped tip of an iron pontil rod was slightly cooled then dipped in sand (or small glass chips) prior to application to the bottle base (Van den Bossche 2001).  The sand/glass chips were apparently intended to keep the pontil rod from adhering too closely to the bottle, facilitating easier removal.    

Found this link in the page bat20 mentioned: "sand pontil scar" 

[flying free]

Thank you Pamela