A Vishay FAQ document does say that a short duration reverse voltage is tolerable: (page 5 lower/page 6 upper)
https://www.vishay.com/docs/40110/faq.pdf.
'
Solid tantalum capacitors are capable of withstanding short duration peak voltages in the reverse direction limited to 5 % of the DC rating at +25 °C'
spec
Cornell-Dubilier says (page 5, right column):
https://www.cde.com/resources/catalogs/AEappGUIDE.pdf
"Like aluminum electrolytic capacitors, solid tantalum capacitors
are polar devices (
1 V maximum reverse voltage), having distinct
positive and negative terminals and are offered in a variety of
styles"
Regarding aluminum electrolytics, they say
"Aluminum electrolytic capacitors are polarized and must be
connected in the correct polarity. They can withstand
reverse
voltages up to 1.5 V. Higher reverse voltage can cause failure
by pressure build up and rupture of the capacitor’s safety vent
structure."
This does seem different than "Although never specified, all electrolytic capacitors can safely handle 10% rated V in negative bias."
Wikipedia:
https://en.wikipedia.org/wiki/Electrolytic_capacitor
says:
"Standard electrolytic capacitors, and aluminum as well as tantalum and niobium electrolytic capacitors are polarized and generally require the anode electrode voltage to be positive relative to the cathode voltage.
Nevertheless, electrolytic capacitors can withstand for short instants a reverse voltage for a limited number of cycles. In detail, aluminum electrolytic capacitors with non-solid electrolyte can withstand a reverse voltage of about 1 V to 1.5 V. This reverse voltage should never be used to determine the maximum reverse voltage under which a capacitor can be used permanently.
[49][50][51]
Solid tantalum capacitors can also withstand reverse voltages for short periods. The most common guidelines for tantalum reverse voltage are:
- 10 % of rated voltage to a maximum of 1 V at 25 °C,
- 3 % of rated voltage to a maximum of 0.5 V at 85 °C,
- 1 % of rated voltage to a maximum of 0.1 V at 125 °C.
These guidelines apply for short excursion and should never be used to determine the maximum reverse voltage under which a capacitor can be used permanently."