Glass samples were delivered polished to the specified polishing conditions. Each glass sample was weighed using a analytical balance. One sample of each glass type were hung by platinum wire into 0.5 mol/liter Nitric Acid at 25 deg C for the length of times specified: 0.1 hour, 1 hour, 10 hours or 100 hours (in the supplied standards, a second set of time intervals were given, 10 minutes, 100 minutes, 16 hours and 100 hours. Readings will be taken at the 100 minutes and 16 hours in addition to the 1 and 10 hours).
After this treatment, the samples were weighed again and the loss of the mass of the sample were calculated. Calculation of the time t0.1 in hours, necessary to etch a surface layer a depth of 0.1 um was done using the following formula:
t0.1 = (tedS)/[(m1-m2)*100]
where:
t0.1 = the time (min) necessary to etch a surface layer to a depth of 0.1 m
te = the time (min) for attach in the experiment
d = the specific gravity of the sample
S = the surface area (cm2) of the sample
m1 = the mass (mg) of the sample before the test
m2 = the mass (mg) of the sample after the test
Acid Resistance Class PR 1 2 3 4 5
Time t0.1 needed to etch to a depth of 0.1um/min >100 10-100 1-10 0.1-1 <0.1
In addition, changes in the surface of the sample following the treatment are qualitatively evaluated with the naked eye. Additional classification numbers are given according to the second table.
Additional Number Changes in the Surface
.0 No visible changes
.1 Clear, but irregular surface (wavy, pockmarked)
.2 Interference colors (slight selective leaching)
.3 Tenacious thin whitish layer (stronger selective)
.4 Loosely adhering thick layer (surface crust)
The target weight loss of 0.0010 grams (1 mg) was met by sample D after 60 minutes, for sample B after 100 minutes, for sample A after 10 hours, C and 2 after the 100 hours. All samples had no visible change at the point when they lost the 0.0010 grams.
The tables list the amount of weight loss after each time interval.
| time (te)
|
0.1 hour
|
|
|
| sample id
|
m1
|
m2
|
m1-m2
|
| A
|
3.8238
|
3.8231
|
0.0007
|
| B
|
3.855
|
3.8546
|
0.0004
|
| C
|
3.8182
|
3.818
|
0.0002
|
| D
|
4.1163
|
4.1157
|
0.0006
|
| 1
|
6.3684
|
6.3683
|
0.0001
|
| 2
|
1.2347
|
1.2339
|
0.0008
|
| 3
|
1.2177
|
1.2175
|
0.0002
|
| 4
|
1.2542
|
1.2541
|
0.0001
|
|
|
|
|
|
| time (te)
|
1 hour
|
|
|
| sample id
|
m1
|
m2
|
m1-m2
|
| A
|
3.8238
|
3.823
|
0.0008
|
| B
|
3.855
|
3.8544
|
0.0006
|
| C
|
3.8182
|
3.8178
|
0.0004
|
| D
|
4.1163
|
4.1151
|
0.0012
|
| 1
|
6.3684
|
6.3678
|
0.0006
|
| 2
|
1.2347
|
1.2338
|
0.0009
|
| 3
|
1.2177
|
1.2173
|
0.0004
|
| 4
|
1.2542
|
1.254
|
0.0002
|
Calculation of t0.1
| Sample
|
Classification
|
density
|
surface area
|
time
|
t0.1
|
|
|
|
|
|
(d)
|
(S)
|
d*S
|
(te)
|
te*d*S
|
te*d*S/[(m1-m2)*100]
|
| A
|
SR2.0
|
3.22
|
45.662
|
147.032
|
10
|
1470.3
|
11310
|
.
| time (te)
|
16.7 hours
|
|
|
|
| sample id
|
m1
|
m2
|
m1-m2
|
|
| C
|
3.8182
|
3.8175
|
0.0007
|
|
| 1
|
6.3684
|
6.3678
|
0.0006
|
|
| 2
|
1.2347
|
1.2338
|
0.0009
|
|
| 3
|
1.2177
|
1.2173
|
0.0004
|
|
| 4
|
1.2542
|
1.254
|
0.0002
|
|
|
|
|
|
|
|
| time (te)
|
100 hours
|
|
|
|
| sample id
|
m1
|
m2
|
m1-m2
|
|
| C
|
3.8182
|
3.8169
|
0.0013
|
>0.00010
|
| 1
|
6.3684
|
6.3677
|
0.0007
|
|
| 2
|
1.2347
|
1.2336
|
0.0011
|
>0.00010
|
| 3
|
1.2177
|
1.2173
|
0.0004
|
|
| 4
|
1.2542
|
1.254
|
0.0002
|
|
Calculation of t0.1
| Sample
|
Classification
|
density
|
surface area
|
time
|
t0.1
|
|
|
|
|
|
(d)
|
(S)
|
d*S
|
(te)
|
te*d*S
|
te*d*S/[(m1-m2)*100]
|
| C
|
SR1.O
|
2.76
|
45.7
|
126.03
|
100
|
12602
|
96944
|
| 2
|
SR1.0
|
2.23
|
42.3
|
94.39
|
100
|
9438
|
85809
|
Comparison of Glass Types
| Sample
|
Class
|
Sample
|
Class
|
Notes
|
| A
|
SR2.0
|
1
|
SR1.0
|
Did not exceed 1 mg
|
| B
|
SR3.0
|
2
|
SR1.0
|
|
| C
|
SR1.0
|
3
|
SR1.0
|
Did not exceed 1 mg
|
| D
|
SR4.0
|
4
|
SR1.0
|
Did not exceed 1 mg
|
Three supplied samples, 1, 3 and 5, did not exceed the 1 mg weight loss and would be classified as SR1.0 as no visual degradation was observed. In addition, samples 2 and C only exceed the 1 mg level after 100 hours of soaking and would be classified as SR1.0. Sample A was classified as SR2.0, sample B as SR3.0 and sample D as SR4.0.