Button-fixes are very strong, but there are too many variables to be specific about a safe loading for your individual application.
For thinner panels and low-strength materials like particle-board, the limiting factor dictating the maximum load will be the pull-out strength of the screw fixings. Therefore, the fixings used should be the largest practical, given the thickness of the substrate/panel to be mounted. Assuming that the substrates/panels are strong, the appropriate fixings are used and applied correctly, sufficient Button-fixes are used and a conservative safety margin is applied to the test data available on this site, then you should have no problems with weight loading. This will be particularly true if the panels are vertical and there is no cantilever component to the loading. However, if the panels are not vertical and/or there is a cantilever load, then you should rigorously test the application to your own satisfaction before proceeding.
For Type 1 Fixes, ‘Buttonfix strength testing report’ is available here.
Also, have a look at a typical example of the independent load testing carried out on the Type 1 Fix here.
The Type 2 Fix is ideal for applications where the emphasis is on ease of fit rather than strength. Assuming that the screws and substrate are properly matched, a vertical panel under no other loading than its own weight, fixed with four Type 2 Fixes, can safely weigh 80kg. Other configurations should always be tested by the user.
Each Type 2 Fix requires approximately 12kg force to separate the Button and Fix; this should be taken into account when designing your installation and defining your safety factors. Type 2 Fixes should only be used on vertical panels or in applications where the weight of the panel does not act to separate the fixing. In critical applications, always use the safety cord accessory.
Please note that safety cords are sold separately from the Button-fixes.