- last price $39.95
A Very Strong (~20,000 psi @ 3100°F) Self-Levelling, Flux Tolerant, High Alumina (70%) Castable Refractory. Primarily a very fine castable powder (+ very few small aggregates).
TIP: Though very LITTLE water is required, typically approx 8-10% gives best results in practice (on paper it recommends 5-8%), mix for a full 5 minutes, and you often find that even with 8% water to start, the mix looks VERY VERY dry, and that it will need gallons of water... but wait ... as if by magic, at 3 minutes the refractory blend will 'liquify'.
Ultra Express 70 is ideal for ribbon burners because it flows more easily through the straws or crayons than 'thicker' blends.
UX-70 is part of a unique group of refractories that become stronger at higher temperatures. Most people find that an extra drop or two of water gives cleaner castings than casting too dry, especially without a vibration table. UX-70 has more strength than most projects require, and the fractional loss in strength is incidental and secondary to a well-formed cast.
If you find a small skim of water forms above your casting, ignore it. It will help prevent spalling during curing and disperse naturally.
Note that the fibres in the mix are designed to allow water vapour to wick out of the castable during drying, helping to prevent steam-based explosions that can result from rapidly heating castings with trapped water.
Ultra Express 70 is very tolerant of Welding Flux. Though welding flux may stick, it won't penetrate or destroy it, as flux does to most (especially insulating) castables. GreenCast 94+ (& GR+) have close to the same physical properties, but 94% alumina, and welding flux not only will not damage GC94, but it will lift off of it like eggs off a Teflon skillet, especially if vibration cast to avoid small surface air pockets that can trap molten flux.
UX-70 becomes so dense (and strong), that a 50 lb bag does not go as far as you'd think. Add water, it condenses, filling the bottom square 1 cubic foot box only 3.75". (density is ~160 lb/cubic foot). TIP: Its so strong, we often use it in layers.
It's a versatile, easy-to-use refractory, and one of our favourite, serious castables.
Click here for SDS.
