Electrolytic capacitor manufacturers say that if you energize them before 2 years or 1 year of storage (5-35C minus 75% RH) there is no need to refurbish the capacitor.
Is this only valid for new aluminum electrolytic capacitors with little or also for old capacitors from the 90s and mounted on an electronic circuit that operates at 220V?
In electronic devices and connected to 220V, how many minutes are necessary to restore the entire dielectric oxide layer (it degrades in storage)?
Give it a go @ EE Stack Exchange or @ EEvblog.
Sorry I cannot answer your question as I do not know the make or values etc. Have you checked with the manufacturer of the particular capacitor you have?
I got this from the internet, hopefully it gives you an idea of what you asked.
Aluminum electrolytic capacitors come in several types, distinguished by their construction, electrolyte, and intended applications. Here's a breakdown of the main types:
Non-solid (Wet) Aluminum Electrolytic Capacitors Most common and inexpensive. Liquid electrolyte. Used in power supplies, audio equipment, etc. Prone to drying out over time.
Solid Aluminum Electrolytic Capacitors Conductive polymer instead of liquid electrolyte. Lower ESR (Equivalent Series Resistance). More stable, longer lifespan, better for high-frequency applications. Often used in motherboards, VRMs, and SSDs.
Hybrid Aluminum Electrolytic Capacitors (Polymer Hybrid) Combine liquid and solid electrolytes. Balance between cost, performance, and lifespan. Lower ESR than wet types, but more affordable than pure polymer types.
SMD (Surface Mount) Aluminum Electrolytic Capacitors Come in both wet and solid/polymer versions. Designed for surface-mount technology (SMT). Used in compact electronics and automated assembly.
Snap-In / Screw Terminal Aluminum Electrolytics Typically larger values (high capacitance, high voltage). Used in power supplies, industrial equipment, and audio amplifiers. Designed for through-hole mounting and mechanical stability.
Each type has different voltage, capacitance, and ESR characteristics, so the "right" type depends heavily on your specific application.
bypass and coupling capacitors can need as much as 24 hours to restoring dieletric layer?
I never heard of those types of capacitors before, where can I find them?
Hi, @aranbafdan88
Is there a reason you have all these threads open about longevity and storage of components?
Tom.... 
They are not types of capacitor they are the uses to which capacitors are put.
The question was for OP.
In which case the answer you gave is nonsense.
If they been connected to 220 for the past 35 years I think you are lucky they are still good.
Coupling capacitors are used in series to allow only high-frequency signals to pass to the system load, as in the following image. Decoupling capacitors, also known as bypass capacitors, have the opposite function to coupling capacitors.
Do these capacitors need to be energized for a longer period of time (24 hours) compared to common ecaps to prevent the need for reform?
I would say not.
My direct experience of being forced to use an inadequacy capacitor in set top boxes was the capacitors eventually failed, no surprise.
But the big surprise is that if the set top box was left for 6 months or so, the set top box would work again for another month before they failed.
If you want to reform an old system, that was in the pre buck / boost era, then you could by powering the system with a reduced voltage, and slowly increasing this over a day or so. To do this you would have to use a Variac transformer.
Beware of other experts on this thread that only have book learned stuff on this topic, with no practical experience on the topic.