Is Silica Gel fit for Ultra-High Dessication?

I had the (perhaps wrong) notion that silica gel wasn't that strong of a dessicant, especially compared to CaO, MgO, CaSO4, H2SO4, KOH, Mg(ClO4)2), but I've been exposed to information\* that might give me wrong.


Can silica gel beat most of those dessicants in terms of residual water in a dried solid? Can silica gel really be used to dry salts down to only twice the residual water level that can be achieved with Mg(ClO4)2 and half the residual water level than can be achieved with KOH as dessicant? Or does that only apply to air/gases?


Will anhydrous silica gel allow to dessicate compounds that have high affinity to water down to very low residual water levels? (when used at say 5-20C at atmospheric pressure on salts pre-dried with MgSO4)


What are the conditions that give silica gel its greatest capacity to dessicate salts to ultra low residual water levels?




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\*Merck Memento, p14, says:


Residual humidity in mg H2O /L of air after dehydration at 25°C:


* White CuSO4 1,4
* Molten ZnCl2 0.8
* CaCl2 0.14-0.25
* CaO 0.2
* Molten NaOH 0.16
* MgO 0.008
* Anhydrous CaSO4 (plaster of Paris) 0.005
* Concentrated H2SO4 (95-100%) 0.003-0.3
* Dry Al2O3 0.003
* Molten KOH 0.002
* Silica gel (SiO2) 0.001
* Anhydrous Mg(ClO4)2 0.0005
* P2O5 below 0.000025




Silica gel is really one of the best desiccants known. But it has to be thoroughly dehydrated at high temperature. Usually silica gel contains a small amount of cobalt chloride $\ce{CoCl2}$ : blue when anhydrous, and red when hydrated. Silica gel should not be used if reddish. It has to be blue to act as desiccant.


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