In short: amazingly good strings at a reasonable price.
Description
The white pearloid trebles and the basses core are made of nylgut. Compared to real gut, this synthetic material is more resistant and similar in density and specific weight.
Tension
On paper this low tension pulls 41,10 kgs: slightly more than the famous Augustine Classic Blue, definitely more than some normal and even high tension sets (e.g. D'Addario EJ45 & EJ46, Savarez 500CR & 500CJ).
Practically things are different. Nylgut stretches under tension more than nylon, so the nominal tension of the Alabastro drops when they are installed and in tune.
How to install them
As suggested by the producer, these strings should be kept tense then attached to the rollers, tuned and stretched several times above the 12th fret. They are really elastic (especially the trebles) so the trick is to give them some tension before using the tuners. After a couple of days the tuning will settle in. If on the contrary you keep them slack and start winding, the pitch will be probably decreasing for days.
First impression
Overall they don't feel too soft (my favourite tension is more or less in the 40-42 kgs range). Nylgut trebles react to plucking, apoyando and arpeggios with moderate resistance, which is good.
Sound
I have been using for a while the Alabastro on two different classical guitars (cedar and spruce top) and they are wonderful on both of them: a
surprising alternative to nylon strings. I cannot make a comparison with fluorocarbon strings, never used them.
In my opinion the Alabastro have great features: powerful basses and middle tones, clear trebles, strong attack and projection, remarkable sustain. With these strings you can play quite loud and be expressive at the same time: nylgut responds well to changes of dynamics and different fingernail angles.
To my ear (and to the ears of my very small, very devoted audience) the tone is lavish. More brilliant and "thicker" that than of some famous good quality nylon sets. Overtones in real gut strings are cut at a higher threshold than in nylon strings. Chances are the same happens to nylgut. Or is it the placebo effect? A spectral analysis would clarify but that's not my field.
Duration
Average.
After roughly 60 hours of playing the beautiful tone was still there, the projection was obviously reduced, the 4th and 5th strings were oxidated and their winding was worn out over some frets so I replaced them with spare strings. The 6th string and the trebles were still ok.
Value for money
Excellent: good quality strings can be more expensive than the Alabastro.
Anything negative?
I wouldn't say these strings have a short life, however I sure wish they could last longer.