A main feature of bottles like this one is that they have no striping to the shank of the stopper and the well / neck section of the body. Another feature is that the canes do tend be of lesser quality in their structure and the setting within the bottle.
But generally I suspect that all such bottles that are clearly not by Paul Ysart and ALSO satisfy the standard UV testing for pre-1956 Ysart items, were made by Salvador Ysart.
The quality, and the setting of canes in "Salvador bottles" can vary greatly. Some are almost as precise as Paul Ysart's work. Others are of "average quality". And some have a good colour balance, while others are quite unattractive. In some cases the striping can be "washed out" and unimpressive.
In the case of the bottle for this thread, I agree with Alan that the coloured chips are a feature that strongly points to Salvador Ysart as the maker.
As for the dating of Salvador Ysart bottles, there is definite evidence of some (and, I guess, most) being made in the Ysart Brothers period (i.e. post-war). However I have seen no definite evidence to say, one way or the other, whether Salvador made such bottles in the pre-war years. My guess is that he did, but I know of no way to identify them as such.