View Single Post
Old 12-19-2018, 10:58 PM
Lynn Read Lynn Read is offline
Registered User
Join Date: Aug 2008
Location: Portland, OR
Posts: 17
Lynn Read is on a distinguished road
Originally Posted by Jordan Kube View Post
So I melted this 5% opal the other day:

In pounds
Sand 7.3125
Soda Ash  2.38875
Potassium Carbonate 0
Calcium Carbonate 0.4125
Strontium Carbonate 0.675
Zinc Oxide 0.225
Alumina Hydrate 0.3375
Lithium Carbonate 0.075
Antimony 0.03975
Potassium Nitrate 0.075
Sodium Tripolyphosp. 0.93

Total 12.471

Oxides %
SiO2 66.86
Na2O 16.4
K2O 0.327
LiO 0.278
CaO 2.13
MgO 0.006
SrO 4.35
ZnO 2.06
Al2O3 2.229
P2O5 4.95
Sb2O5 0.365

Charged a few scoops at 2300 every two hours. Held at 2300 for 10 hrs and then down to 2150. It came out pretty scuzzy on top like you guys talk about some phosphates coming out. It was also pretty streaky in coloration and cordy looking. It blew out ok and the stuff I made into bar struck out beautifully after being picked up again, as always. As a note, I ground the STPP in a bullet blender in an effort to avoid some chunkies I was getting in the 2.5% melts. It also came out 4 points high after my educated guess on adjustment. Based on that and my percentages I'm thinking at least adding some silica is in order.

Any thoughts on cleaning this one up?
Hey Guys, Jordan and Pete,

I have been reading this thread and wanted to ask if you think this Sagahara glass is a Na5P3O10 opal (STPP)? It has so many amazing hues of blue and golds but the density is so slight I would imagine it must be only .5 %- 1% max phosphate. Based on the images that Jordan posted at 5% I would be far to dense.

I want to run some test melts but trying to gain some feedback first. I will be press molding the glass with a wall thickness of 1.2" - 3/4" thick so I need to limit the saturation. I will be cycling the glass through a cold work process and a second firing for my final fire polish. I am sure the duration of heat cycles will effect the opacity with this glass. I am hopeful that I can get a nice pale smokey white.

Any advise would be helpful in regard to % of STPP or strategies to get the shift if warm and cool tones. Maybe it is just the shape of the glass refracting color.
Attached Images
File Type: jpg Sagahara opalescent vase.jpg (24.5 KB, 60 views)
Reply With Quote