Magnesite & Synthetic Frankfurt Abrasives for Hard Granite Polishing

The program assigns each abrasive family one job, in order. Stage one is grinding with magnesite: the early heads carry 24# through 320# in steps, removing saw and calibration marks and closing the scratch pattern gradually. Line operators start coarse and only move to the next grit when the previous pattern is gone, because a skipped step resurfaces later as scratches the fine polish cannot hide. Stage two is fine polishing with synthetic: heads carry 400# through 2000#, each step erasing the previous scratch pattern until the surface is uniform enough to take a gloss reading. Stage three is the final polish with oxalic acid blocks in 5 Extra or 10 Extra grade, which act as a chemical auxiliary: during the last passes the acid phase works the granite surface to draw out the final gloss. Practical checkpoints: verify gloss on the first slab of each grit change, keep water steady at every head, and track consumption per head so reorder quantities follow the program instead of guesswork.

You rarely need all sixteen steps — the sequence is trimmed to the stone and the target gloss. For hard granite, a typical line uses four to six magnesite steps from the 24#, 36#, 46#, 60#, 80#, 120#, 180#, 240# and 320# range — starting near 24#–46# when saw marks are deep, or near 80#–120# when slabs arrive well calibrated — then three to five synthetic steps from the 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# range, and finally 5 Extra or 10 Extra oxalic acid. How to trim: harder, more abrasive granite consumes blocks faster and usually justifies more magnesite steps with smaller grit jumps; softer stone lets you skip grits and move to synthetic earlier. Dark granites chasing a mirror finish run deeper into the 1500#–2000# synthetic range, while commercial slab grades often stop near 1200#–1500#. What to confirm before fixing the sequence: incoming slab flatness, target gloss specification, machine head count and the water condition, since slurry behavior shifts effective cutting at every step.

Send five items first: stone type, machine model and head count, current grit sequence, monthly polished area and target gloss. Stone type or a sample photo determines the magnesite-to-synthetic split and the step count. Machine model and Frankfurt head holding confirm format compatibility and how many heads are available for each stage. Your current grit sequence — or a photo of the blocks you run today — lets DINOSAW map your existing program onto the 24#–320# magnesite, 400#–2000# synthetic and 5/10 Extra oxalic ranges without re-engineering from zero. Monthly polished area converts directly into block quantities per grit for a realistic first order and a reorder plan. Target gloss sets whether the synthetic range stops near 1200# or runs to 2000#, and whether 5 Extra or 10 Extra oxalic acid is recommended. Also useful: destination country for packing and logistics, photos of polished slabs showing any current defects, and your consumption records if you already track them — with these, the quotation comes back as a complete per-head consumption table rather than a unit price list.

Because at the grinding steps, the cheap fast-wearing block is often the economically correct answer. Magnesite is the most historical grinding and polishing material for granite: the operating skills around it are mature, every line operator knows its behavior at each grit, and it still occupies a large proportion and volume in hard-granite polishing for one structural reason — removal duty destroys abrasive quickly, so paying a long-life resin price at a grinding head spends money on durability the process immediately consumes. The traditional program resolves this by division of labor: magnesite does the grinding from 24# to 320# where cost per removed volume rules, synthetic does the fine polishing from 400# to 2000# where surface quality rules, and oxalic acid closes the final gloss. Resin and metal tools keep their place — metal for shape-stable heavy removal, resin for long-life fine polish — but a factory polishing hard granite slabs in volume will typically spend far less per square meter with the magnesite program at the grinding heads, accepting more frequent block changes in exchange.