Lithopone in paint: uses and formulation guidance
Review the role of lithopone in interior paints, its limits versus titanium dioxide, and a controlled approach to dispersion and formulation trials.
What does lithopone do in paint?
Lithopone is a white pigment based on co-precipitated zinc sulfide and barium sulfate. In suitable paint systems it can contribute whiteness, body and opacity as part of the overall pigment package. It should be assessed within the complete formulation, including binder, extenders, dispersants and other additives.
The objective is a coating that meets its intended specification at an acceptable total cost. Loose-powder whiteness alone does not predict the appearance or durability of a dried paint film.
Lithopone and titanium dioxide serve different roles
Titanium dioxide generally provides stronger light scattering than lithopone. Suitable rutile grades are widely considered where high hiding power or demanding durability is required. Lithopone can be evaluated in selected interior and other appropriate systems, but a universal substitution ratio cannot be assumed.
For exterior topcoats, include weathering and colour stability in the assessment. Do not transfer an interior result directly to a sun-exposed façade or industrial product. Longtai’s coatings application guide and product catalog help identify options for discussion.
A controlled formulation trial
- Define the reference paint and the required dry-film properties.
- Review the pigment specification and SDS before handling.
- Prepare a dispersion using the intended binder or dispersing medium.
- Change pigment proportions in planned steps while recording the pigment volume concentration.
- Produce test films at a consistent thickness and curing condition.
- Compare optical, application and durability results before moving to a production trial.
Record grinding conditions and any changes in viscosity or binder demand. There is no single addition rate that applies to all emulsions, enamels or substrates.
What to measure in the finished coating
| Assessment | Reason |
|---|---|
| Dry opacity and colour | Shows whether the formulation reaches its visual target. |
| Gloss or sheen | Can reveal changes in dispersion and pigment packing. |
| Application and rheology | Checks flow, levelling and processing behaviour. |
| Scrub, adhesion and film properties | Checks requirements that appearance alone cannot establish. |
| Storage and exposure stability | Helps identify settling, viscosity change or colour instability. |
Common mistakes to avoid
Do not judge the pigment using an unrelated test method, compare coatings at different film thicknesses or reduce binder solely to offset a change in powder cost. Skipping dispersion evaluation can produce a poor result even when the grade is otherwise suitable.
When selecting between B-301 and B-311, use current product data and your own application results. Discuss unusual processing conditions or end-use requirements before ordering.
The NIST Chemistry WebBook: zinc sulfide provides an identity reference for a lithopone constituent. Chemical identity alone cannot predict opacity, durability or the substitution ratio in a paint formulation.
Frequently asked questions
Can lithopone fully replace TiO2 in paint?
That depends on the target, and a complete replacement should not be assumed. Evaluate opacity, durability and total formulation cost.
Is lithopone automatically suitable for exterior paint?
No. The grade and complete coating need testing for the actual exposure conditions.
Can Longtai help select a starting grade?
Discuss your application with Longtai Chemical. Include the target grade, required quantity, packaging and destination port so the team can prepare a relevant product recommendation and quotation.
