Ricing

The batch fills with small hard grains that look like rice, usually seconds after the fragrance went in.

Small hard lumps

Distinct from seizing: the batch is still fluid but full of solid particles that will not blend out.

Poured as it is, the bar has a gritty texture and a speckled cut face.

What causes it

A fragrance oil interacting with the batch, which is the usual explanation and is the one to plan around.

Sometimes a hard oil solidifying because the batch was too cool, which is really false trace wearing a different appearance.

Occasionally a colorant that was not dispersed.

What to do

Blend hard with the stick blender. Ricing frequently blends smooth where seizing does not, and a batch that rices can often be recovered completely.

Warm it gently if the cause was cool hard oils.

If it will not blend out, pour and accept a rustic bar, or divert to hot process, where the cooking resolves it.

Preventing it

Test new fragrances in small batches.

Work within the temperature range rather than below it, since a cool batch is the other cause.

Disperse colorants properly.

And note which fragrances riced, because they will rice again and the second time should not be a surprise.

References