Whereas , in the current state of analytical techniques , it is not possible to determine all the conditions under which conventional migration tests should be performed on materials and articles consisting of two or more layers , one or more of which does not consist entirely of plastics; whereas a decision on the application of this Directive to such materials and articles should therefore be taken at a later date.
The above sentence is very complicated. Please provide me a simplified synonymous version consisting of multiple sentences:
The current state of analytical methods does not allow all the conditions to be specified under which conventional migration tests are to be carried out on materials and objects which consist of two or more layers , at least one of which is not exclusively made of plastic . Therefore , the application of this guideline to these materials and objects must be decided at a later date .