We have 11 colours of Gypsogem Pigment iron oxide powder 50ml for our Gypsogem Eco Powder for you to choose from.
When you add Gypsogem Pigment oxide powder to our Gypsogem Eco Resin (sold via this platform), the pigment will mix with the gypsum-based material to create a colored paste. The intensity of the color depends on the amount of pigment powder you add. It's recommended to start with a small amount and gradually increase it to achieve the desired shade. Adding too much pigment might affect the consistency and drying time of the mixture.
Each colour sold seperatly.
Just a quick note on pigment behaviour in gypsum:
Because gypsum is naturally white, any pigment mixed into it will result in a pastel version of that colour. The more pigment you add, the deeper the pastel shade becomes-but it will still be a toned-down version of the original. For example, red will appear more pink, and blue will lean toward baby blue. With this type of pigment, achieving a true, saturated colour isn't possible unless you're working with a neutral or darker base.
Staining of moulds
Staining is usually caused by the type of pigment used (water-based, oil-based, or highly concentrated dyes) and whether the pigment migrates into the porous surface of the silicone. Gypsum grade (fine cast, alpha, beta, etc.) affects smoothness, strength, and setting time, but not pigment transfer.
Why Staining Happens
- Pigment CompositionWater-based pigments are less likely to stain silicone because they wash out easily.
Oil-based or alcohol-based pigments can seep into silicone pores and leave residue.
- Silicone QualityHigh-quality platinum-cure silicone moulds are more resistant to staining.
Lower-grade or older moulds may absorb pigment more readily.
- Mixing RatioOverloading gypsum with pigment increases the chance of pigment bleeding into the mould.
Balanced ratios (powder-to-water and pigment-to-mix) reduce staining.
Practical Tips for Preventing Stains
- Seal the mould: Apply a thin release agent (e.g., petroleum jelly spray or commercial mould release) to create a barrier.
- Test pigments: Always test a small batch before committing to a full pour.
- Clean promptly: Wash silicone moulds immediately after demoulding to prevent pigment setting.
- Use high-quality pigments: Craft pigments designed for gypsum/resin are less likely to stain compared to generic inks or fabric dyes.
Bottom line: The pigment type and concentration are the main culprits for staining, not the grade of gypsum powder. If you're using water-based craft pigments with fine cast gypsum in a platinum-cure silicone mould, staining risk is minimal.
Oxide Pigments in Gypsum Casting
- Nature of OxidesOxide powders (like iron oxide, titanium dioxide, chromium oxide) are inorganic mineral pigments.
They are highly stable, UV-resistant, and don't dissolve in water-they remain as fine particles suspended in the gypsum mix.
- Interaction with Silicone MouldsBecause oxides are particulate, they don't "bleed" into silicone the way liquid dyes or alcohol inks do.
However, if used in high concentration or if the mould surface is slightly textured/porous, fine oxide particles can lodge into microscopic pores and leave a faint residue.
Dark oxides (e.g., red iron oxide, black iron oxide) are more likely to leave visible traces than lighter ones (like titanium dioxide).
- Cleaning & Release AgentsA good mould release spray or barrier coat prevents oxide particles from sticking.
Washing the mould immediately after demoulding usually removes any residue.
Platinum-cure silicones are more resistant to staining than tin-cure silicones.
What's in the box
1 x 50ml of the Gypsogem Pigment Iron Oxide Powder
