You can provide additional shielding for an HDMI cable by wrapping it with aluminium tape. The aluminium in the tape acts as an additional shielding layer similar to the internal foil layers. However, double- and triple-shielded HDMI cables can be purchased at a cost comparable to the aluminium tape, which makes the practice economically inefficient. HDMI cables typically include two layers of shielding -- foil and braid -- designed to block high- and low-frequency interference.
Unplug the HDMI cable from any connected devices and place it on a flat surface.
Wrap the aluminium tape around the circumference of the HDMI cable at the edge of the wire parallel to the connector. Leave the connector element exposed.
Continue to wrap the tape around the wire section of the HDMI cable so that the entire cable is covered while overlapping the tape as little as possible. Circle around the circumference of the wire at approximately a 30- to 45-degree angle, depending on the width of the aluminium tape.
Wrap a single layer of aluminium tape around the edge of the wire section so the edge of the tape is parallel and against the connector section.
Cut the end of the aluminium tape with a pair of scissors. Wrap the excess tape around the wire so it lays flat.
Keep the cable straight when wrapping to keep the tape from bubbling. Bubbles in the tape can come loose and expose the cable. Additional shielding is more important for longer cables. Cables shorter than 16 feet do not need more shielding than is provided by the manufacturer. Additional shielding will not help HDMI cables block external interference as it would with coaxial cables because HDMI is a digital connection rather than analogue. However, the additional shielding helps protect the signal in the HDMI cable and allows the cable to send the signal over substantially longer distances when compared to unshielded or less-shielded connections. Although adding extra shielding to the cable generally won't improve performance, this method can be used to replace shielding if the HDMI cable is cut or damaged. Adding a layer of aluminium tape to the cable will make the cable harder to bend, making it more difficult to manipulate the positioning of the cable.
Dots and most other screen distortions over an HDMI connection are not usually caused by electrical interference; rather, they are most often caused by damage to the HDMI cable. The cable can be damaged by excessive bending and improper storage wrapping techniques.