Coloured Infrared Filters
Tiffen Infrared Orange
There are a number of infrared filters made by the big companies which you may have seen. Examples of these are the Hoya R72, B&W 099 and 091.
These filters are not "black infrared" filters and therefore cannot be used for infrared x-ray. The reason is that they allow light past which is within the visible spectrum. If you hold these filters up to your eye you can see through them. Only consider a filter which is totally black to the eye. You should not be able to see anything through it at all.
Please note - when examining a filter which is black to the eye, never look at the sun through it. Doing so will flood your retina with extremely intense infrared light which you cannot see and can cause serious damage and possibly blindness!