The best way to know if your wig is heat resistant is by checking its packaging or tags for specifications. Or, you can contact the company you bought it from and ask if the wig is heat resistant. Another way to determine a heat-resistant wig is by doing a heat test. I recommend a heat test on a small section of the hair so you don’t turn up the heat too high. Otherwise, you might burn the hair and end up damaging the wig. Usually, synthetic hair can safely straighten at a temperature below 350 degrees Fahrenheit.