Answered By: Beth Hylen
Last Updated: Mar 17, 2017     Views: 1761

Many artists today are "tumbling" glass fragments to create "beach glass" -- it takes just a few hours in a tumbler. 

From: http://www.dadsrockshop.com/faq/faq_tumblers.html#12 

"I'd like to make "sea glass" especially blue stuff which is hard to find on the sea shore. Can I tumble glass shards (say from a Harvey's Bristol Cream bottle) with SAND in one of your Lortone tumblers to get the "all-over rough" feeling of natural sea glass? 
Yes you can. We have hundreds of customers doing this type of process. Some use sand, most use a coarse to medium fine silicon carbide grit to get the beach glass effect they desire. You may want to experiment with different grits or polishes to get your desired result. This is normally a quick and easy process. I would recommend a rotary style unit like the Lortone 3A. The size or capacity of the tumbler you might select will depend on the size of the glass pieces and the amount that you want to process at one time...." 

More detailed instructions: http://web.archive.org/web/20090717063915/http://www.mamasminerals.com/issuesum2003.html#howto


In nature, the time would depend on the composition of the glass and it's hardness/softness. Most bottle and tableware glass is a "soda lime" composition which is fairly soft. It probably etches relatively quickly when it is dragged across sand and rocks by waves. 

There are many factors that contribute to the formation of what is known as smooth beach or sea glass when considering man made glass just read the information below taken from the text Pure Sea Glass Discovering Natures Vanishing Gems By Richard Lamotte:

"Tidal shifts, currents, and wave movements along rough shorelines mutually assist in the physical conditioning of glass. It is not just the pounding surf that created the soft, round edges of glass shards. Significant abrasions happen when glass moves laterally within the littoral zone, just offshore. Strong currents and wave action increase the overall natural etching of sea glass. Glass shards in shallow water will move with greater velocity across an abrasive terrain as compared to shards in deep water. Seashore undertows although dangerous to swimmers  have a string lateral flow that helps create the tumbling of sea glass."

"Conditions of saltwater oceans and estuaries have higher PH Levels which contribute to the overall weathering process of glass. High levels of carbon dioxide in seawater also contribute to the weathering of glass."


I will search for a more accurate answer, but I wanted to get this information out to you. 

You may be interested in our bibliography about beach or sea glass. 

If you wish to obtain copies of any of the items on our list, please contact your local library. The Rakow Research Library is a member of the Online Computer Library Center (OCLC); your library can contact us through OCLC or they may mail an Interlibrary Loan form to us. We send copies of articles and microfiche copies of our books (if they have been microfilmed) through Interlibrary Loan for four weeks use.