A whetstone's grit label and its water instructions answer different questions. Read both before choosing a preparation routine; a number alone is not a soaking instruction.
Technique and structure
A manufactured whetstone has abrasive particles and a structure that holds them. Shapton lists abrasives, binders and other compounds among its stones' main constituents; TOJIRO's technical guide describes the bond as the matrix retaining the abrasive grains and explains that the bond affects grinding behaviour and feel. Grit therefore describes one feature of a stone, rather than its complete construction. The inspected Shapton pages do not identify a specific bond formulation for each listed model, so this guide does not assign a vitrified, magnesia or resin bond to them, or derive a soaking time from an assumed formulation.
Start with the product identity
Shapton lists KUROMAKU Orange K0702 as a #1000 medium stone and Enji K0704 as a #5000 finishing stone. Its RockStar range also uses micrometre-based class information. The FAQ defines that measure as the approximate central abrasive particle size. Keep the range and product code with any grit comparison; these examples do not establish equivalence with another maker's labels.
Separate first use from prolonged soaking
Shapton's website says pre-soaking is unnecessary. Its FAQ adds that five to six minutes in water before the first use can give a smoother sharpening feel. These statements distinguish routine preparation from an optional first-use measure. The same FAQ says not to immerse its stones for 30 minutes or longer because of possible softening.
Read the care limits too
The maker excludes hot water and detergent, warns against rapid fan drying, and specifies indoor storage at room temperature away from direct sunlight. For KUROMAKU, it also says to remove the white transport-foam liner for storage after use.
For international readers
Keep the product code with any grit comparison and follow the actual stone's water and storage instructions. Use these Shapton examples to read a label more carefully, rather than as a soaking timetable for other manufacturers or natural stones. No stock, dispatch or international-delivery claim is made here.
日本語
シャプトン砥石の見方：番手・吸水・保管を確認する
シャプトンの現行製品表とFAQを基に、刃の黒幕の#1000中砥と#5000仕上砥、RockStarの粒径表示を区別します。人造砥石は砥粒とそれを保持する結合材などで構成され、藤次郎は結合材が研削性能や研ぎ味に影響すると説明しています。番手だけで構造や吸水方法は決まらず、個別モデルの結合材は推測しません。シャプトンは事前吸水不要とし、初回5～6分の吸水による滑らかな研ぎ感も案内。30分以上の浸水、熱湯、洗剤、急な送風乾燥を避けるよう指示しています。他社や天然砥石への一律適用はしません。
Sources
Shapton current product ranges