Thank you for posting your feedback. We're sorry to hear about your experience with RapidFuse. Harder (higher density) and/or (low surface energy) slick plastics, such as acetyl, nylon, polyethylene, polypropylene and PTFE can be more challenging to develop proper adhesion without additional surface preparation. Based on your description of the plastic you were intending to bond, you may benefit from the use of the RapidFuse Plastic Primer. At your convenience, please contact DAP’s Technical Customer Service Department at 888-327-8477 so that we can obtain some additional information from you and so that we can provide you with additional usage guidance.