Clear Reichenbach powder—or any clear glass powder—can turn white, milky, or cloudy after fusing for a few reasons.

1. Micro-bubbles trapped between the tiny particles

When you sift or layer clear powder, the tiny grains trap a LOT of air.
 When it fires, that air expands and forms micro-bubbles, creating the appearance of:
·      White haze
·      Frostiness
·      Cloudy or devitrified look
This is the number one reason clear powders look white.
The more powder you use, the whiter it looks

2. High surface-area = higher risk of devitrification

Powder has the highest surface area of any glass form, which means:
·      It picks up contaminants easily (even from the air)
·      It encourages crystal formation on the surface
·      It devitrifies more easily than frit, sheet, or rod
Devit looks exactly like a white matte scum layer.

Over-firing or holding too long near 700–750°C

Reichenbach and the other 96 COE clears can devitrify if exposed too long to:

·      680–760°C (slow ramps, long soaks)
·      Heatwork from multiple firings

Tack fuses are actually riskier than full fuses because the glass spends longer in the danger zone
What can you do to prevent the white haze

A. Use less powder
Thin, even dusting instead of a thick layer.
Thick powder layers always look white.

B. Cap the clear powder
If you need true optical clear, powder under a cap sheet gives vastly better clarity

C. Fire hotter + shorter
A schedule like this helps:

149°C/hr to 675°C – no hold  
333°C/hr to 805°C – hold 10 minutes  
Full to 482°C – hold 60 minutes  
83°C/hr to 371°C – off
Higher top temp + fast heating decreases devit.

D. Consider switching to frit
Clear frit (#1 or #2) stays clear.