Ceramic, Tile & Sanitaryware Manufacturing calculator

Rework Firing Load Time Calculator

Rework Firing Load Time helps kiln supervisors and production planners understand how much schedule time a rework load will consume. It is useful for reglaze, refire, repair, color correction, and second-fire decisions that compete with first-quality production for kiln capacity.

What this calculator does

  • Estimate added kiln or handling time required to refire rework tiles, reglazed ware, or repaired sanitaryware pieces.
  • a kiln team is deciding whether a rework load can fit into the available firing schedule
  • The result estimates the time a rework firing load will consume in the kiln schedule.

Formula used

  • Base rework kiln time = rework pieces to refire ÷ rework firing clearance rate
  • Required rework firing load time = base rework kiln time × rework sorting and kiln-change allowance factor

Inputs explained

  • Rework tiles or fixtures to refire: Count reglazed tiles, repaired sanitaryware, color-correction pieces, or other ware needing another firing.
  • Rework firing clearance rate: Use the rate at which rework ware can be loaded, fired through the kiln slot, unloaded, and cleared from the schedule.
  • Rework sorting and kiln-change allowance: Add allowance for sorting, setter changes, recipe changes, extra inspection, kiln-car handling, and rework paperwork.

How to use the result

  • Use it before approving reglaze, refire, second-fire, or repaired sanitaryware loads that compete with normal production.
  • It does not judge whether rework is technically acceptable and excludes yield loss after refiring unless that loss is handled separately.

Common questions

  • What counts as rework ware? Use pieces that need another kiln pass, such as reglazed tile, repaired fixtures, color-correction ware, or pieces held for a second fire.
  • Should I include sorting time? Yes. Include sorting and staging in the allowance if it is not already part of the measured clearance rate.
  • How can this support a rework decision? Compare the required rework firing time with available kiln capacity and the expected value recovered from the rework load.
  • When is the result only a schedule estimate? It is only a schedule estimate when refire yield, glaze color risk, warpage, or thermal shock risk determines whether rework is worth attempting.

Last reviewed 2026-05-12.