Oxide balance
Oxides from ingredient masses, R₂O and RO totals, melting loss and SO₃ budget, with a live preview while editing.
Batch calculation · W-Make Recipe
Glass batch calculation: from oxide composition to batch weights.
Glass batch calculation converts the target oxide composition into raw material weights, using the analyses of the raw materials. Loss on ignition, moisture and cullet all have to be included. W-Make Recipe does this calculation and keeps every recipe version.
Recipe and oxide balance
As you change the weights, the preview recalculates cost, redox, working point and oxide balance. The result goes out as print, PDF or Excel.
Start from a target composition
You enter the oxide target profile and select the available raw materials. The solver proposes matching quantities. Limits can be set per oxide and raw material.
Viscosity and glass physics
Working point, transition temperature, liquidus, viscosity points, density and durability sit next to the recipe. Estimates are labelled as such.
Redox, colour and fining
A separate area shows the calculated redox state, the colour forecast, the redox-temperature curve and the fining window. Each model is named.
Compare versions
Every save creates a version. The comparison sets weights, oxides and physics side by side and marks the differences.
How batch calculation works
The starting point is the composition of the glass in oxides, for example SiO₂, Na₂O and CaO. Each oxide has to come from a raw material. Soda ash supplies Na₂O, limestone supplies CaO, and both release CO₂ during melting. That is why the batch weighs more than the glass it produces. This loss of mass is called loss on ignition.
Worked example, simplified
We need the weights for 72 kg SiO₂, 13 kg Na₂O and 11 kg CaO, so 96 kg of oxides. The raw materials are assumed to be pure and dry here.
| Raw material | supplies | Oxide share in raw material | Weight |
|---|---|---|---|
| Silica sand (SiO₂) | 72 kg SiO₂ | 100% | 72.0 kg |
| Soda ash (Na₂CO₃) | 13 kg Na₂O | 58.5% | 22.2 kg |
| Limestone (CaCO₃) | 11 kg CaO | 56.0% | 19.6 kg |
| Total | 96 kg oxides | 113.9 kg |
113.9 kg of batch yields 96 kg of glass. The remaining 17.9 kg escapes as CO₂.
What makes the calculation laborious in practice
- 01
Impure raw materials
Real raw materials supply several oxides. Dolomite brings CaO and MgO, feldspar Al₂O₃ and alkalis. Change one quantity and the balance shifts in several places.
- 02
Varying analyses
Each delivery can be composed slightly differently. The calculation is only as good as the analysis behind it.
- 03
Moisture
At the scale, weight includes moisture. The glass calculation uses dry mass.
- 04
Cullet
Cullet brings its own oxides and has hardly any loss on ignition. A high cullet share therefore changes the weights of all other raw materials.
What W-Make Recipe brings to it
Target composition
From an oxide target profile and the available raw materials, a solver (NNLS) proposes the quantities. Tolerances can be set per oxide.
Viscosity and glass physics
T2, T4, Tg and liquidus after Lakatos, a Vogel-Fulcher-Tammann viscosity curve and a comparison curve after Fluegel.
Redox and durability
Redox after Dietzel, hydrolytic class after Vogel, acid resistance to DIN 12116, and a plausibility check against a container-glass target profile.
Versions
Every save creates a version. Several versions can be compared side by side for ingredients, oxides and physics.
Output
Print, PDF and Excel, with an oxide table comparing actual and target. Deviations above 1% are marked in red.
Where the calculation is not enough
Calculated properties are model values from published regressions. They help compare recipes but do not replace a lab analysis or a trial at the furnace. W-Make Recipe is geared to container glass.
Frequently asked questions
+How do you calculate a glass batch?
You set the target oxide composition and divide each oxide quantity by that oxide's share in the raw material. That gives the weight. With raw materials supplying several oxides, this becomes a system of equations that software solves faster and more reliably.
+What is loss on ignition?
Loss on ignition is the share of mass that escapes as gas during melting, mainly CO₂ from soda ash, limestone and dolomite. That is why the batch weighs more than the glass it produces.
+How is cullet included?
Cullet is calculated like a raw material with its own oxide analysis. In W-Make Recipe it forms its own raw material group alongside purchased and in-house material.
+Can the software start from a target composition?
Yes. You set the oxide target profile and the available raw materials, and the solver proposes the quantities. You can then adjust the result by hand and save it as a version.
Further reading
- W-Make Recipe · Next: features and a look at the application
- Batch management and the recipe workbench: why Batch and Recipe are two products
- Request access: All demo instances contain made-up data and are password-protected. Temporary access is available on request.
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