Facade Panel – Rainscreen
Phenolic-bound lignin/sawdust blend with iron oxide pigments. Production recipe for FAC-PNL-CL. Cures via Fenton oxidation then oven post-cure; finished with beeswax / linseed oil blend.
Measured performance
Aggregated across attached testsIngredients
Organized by mixing part · mass% = share of total recipe| Ingredient | Material | Amount | Mass % | Purpose | Cost |
|---|---|---|---|---|---|
Sawdust | Sawdust | 180 g | 23.6% | Structural filler — bulk biomass | $0.090 |
Kraft Lignin | Lignin | 80 g | 10.5% | Binder and matrix stabilizer | $0.160 |
CaCO₃ (Calcium Carbonate) | Additive | 20 g | 2.6% | Stiffener and filler | $0.006 |
CNF (Cellulose Nanofibers) | NC | 60 g | 7.9% | Reinforcement and cohesion | $2.88 |
Borriesperse (Lignosulfonate) | Lignin | 28 g | 3.7% | Water-dispersible binder | $0.042 |
Sorbitol | Additive | 8 g | 1.0% | Plasticizer for flexibility | $0.014 |
Potassium Sorbate | Additive | 1 g | 0.1% | Preservative (mold inhibitor) | $0.008 |
FeSO₄·7H₂O | Additive | 2 g | 0.3% | Fenton catalyst (oxidation) | $0.002 |
Citrate Buffer pH 4.5 (0.05M) | Additive | 10 g | 1.3% | Maintains optimal pH | $0.050 |
Water | — | 92 g | 12.1% | Hydration and flow medium | $0.000 |
| Ingredient | Material | Amount | Mass % | Purpose | Cost |
|---|---|---|---|---|---|
Hydrogen Peroxide (H₂O₂, 3%) | Additive | 25 g | 3.3% | Curing agent (via Fenton reaction) | $0.063 |
FeSO₄·7H₂O | Additive | 2 g | 0.3% | Fenton catalyst (oxidation) | $0.002 |
| Ingredient | Material | Amount | Mass % | Purpose | Cost |
|---|---|---|---|---|---|
Xanthan Gum | Additive | 10.5 g | 1.4% | Viscosity booster (thickener) | $0.126 |
Warm Water | — | 110 g | 14.4% | Disperses xanthan evenly | $0.000 |
Glycerin | Additive | 34 g | 4.5% | Co-plasticizer, flow modifier | $0.085 |
| Ingredient | Material | Amount | Mass % | Purpose | Cost |
|---|---|---|---|---|---|
Beeswax Pellets | Additive | 50 g | 6.6% | Sealant — hydrophobic finish | $0.750 |
Linseed Oil | Additive | 50 g | 6.6% | Sealant — oxidative cure | $0.200 |
Mixing instructions
9 steps · total hands-on time 31 h 17 min- 1Part A dry mix5 minSigma blade mixer, 300 rpm
Combine sawdust, kraft lignin, CaCO₃, borriesperse, potassium sorbate in the sigma mixer. Dry-mix until uniform color.
- 2Part A wet addition10 min22 °C
Dissolve FeSO₄·7H₂O and sorbitol in 92g water with citrate buffer. Add to dry mix and knead until a plastic paste forms.
- 3Part C preparation15 min40 °C
Heat 110g water to 40°C. Slowly sprinkle xanthan gum while stirring at 300 rpm to avoid fisheyes. Add glycerin and continue 5 min.
- 4Combine A + C15 minSigma mixer, 120 rpm
Pour Part C slurry into Part A mixer. Mix on low shear to develop plasticity without breaking sawdust grain.
- 5CNF dispersion10 min
Gradually disperse 60g CNF hydrogel into the mix. Verify no visible agglomerates against a metal spatula.
- 6Part B activation2 min
Just before printing, dissolve FeSO₄·7H₂O in minimal water, then add H₂O₂. Pour into main mix and fold for 2 min. Pot life is ~30 min.
- 7Print + ambient cure24 h22 °C
Extrude to shape. Ambient cure 24h under humid cover (RH > 60%).
- 8Oven post-cure6 h80 °CConvection oven
Transfer to oven. Ramp 5°C/min to 80°C and hold for 6 h.
- 9Part D seal20 min70 °C
Melt beeswax + linseed oil to 70°C. Brush or dip-coat cured part until absorption stops (~2 passes). Cool.
Cost contribution by ingredient
Ranked high to lowBatch economics
Safety
- H₂O₂ + FeSO₄ reaction is exothermic and must be mixed in small batches (<2 kg).
- Use PPE: nitrile gloves, splash goggles, and PFA apron when handling Part B.
- Oven cure releases trace aldehydes — exhaust to scrubber.