A general scaling of the evolution of an exploding liquid jet under an ultra short and intense X-ray pulse from a X-ray free electron laser (XFEL) is proposed. A general formulation of the conservation of energy for blasts in vacuum partially against a deformable object leads to a compact expression that governs the evolution of the gap produced by the explosion. The theoretical analysis contemplates two asymptotic stages for small and large times from the initiation of the blast. A complete dimensional analysis of the problem and an optimal collapse of experimental data reveal that the universal approximate analytical solution proposed is in remarkable agreement with experiments.The damage exerted by blasts in partial contact with deformable objects has been the subject of diverse studies of interest in mining [1], defense [2], or forensic applications [3, 4]. However, probably the strongest scientific interest in a detailed description of the damage caused by intense blasts has recently come with the advent of serial femtosecond crystallography (SFX) [5]. In this application, a microscopic jet produced by Flow Focusing [6,7] and loaded with protein crystal samples is exposed to focused femtosecond X-ray pulses from XFELs with energies in the range of mJ. As a consequence, the jet explodes in a vacuum chamber, generating a blast that splits the jet in two portions. These explosions were admirably reported in detail by [8] from large series of experiments. The use of increasing frequencies of pulsation of XFELs up to the MHz range [9] to maximize the sample hit ratio has challenged the SFX practitioners. The damage caused to the samples upstream of the blast has been the subject of increasing attention [10]. In this work we focus on the evolution of the blast [8] to precisely describe the physics of the process, obtaining the maximum expansion velocities and stresses undergone by the liquid column and the energies involved. To do that, we first propose a general formulation of the problem of blasts in vacuum, partially against deformable objects.General compact formulation of blasts in partial contact with deformable objects.-Consider a finite amount of condensed deformable matter M surrounded by vacuum. An amount of energy E D largely sufficient to vaporize a portion M g of that matter is suddenly injected in it. If part of M g is adjacent or in direct contact with the outer surface of M , it violently expands as a blast both into vacuum and against M (figure 1). The expanding hot gas domain V g (t) can be consider to comprise two virtual subdomains formally defined in the Supplemental Material: (i) V p (t), that pushes and deforms M by dominant pressure forces, and (ii) V e (t), whose mass and energy are constant by definition while it expands into vacuum. Therefore, V e (t) does not make any work on M . Those definitions and their implications do not impose any artificial condition on the natural evolution of the total gas domain V g (t). However, they provide a drastic simplification:as the initial energized ...