Will silicone sealant stick to your plastic?
Check your plastic against the DAP SILICONE PLUS sheet, then choose a tube.
Working with PVC or ABS? Both appear on the adhesion list for DAP SILICONE PLUS Window, Door & Siding sealant. For methylmethacrylate, polycarbonate, polypropylene, polyethylene and polytetrafluoroethylene, the sheet warns that you won't get the best adhesion and compatibility. DAP says you need to evaluate those substrates before you use the sealant.
Start with the plastic's name
“Plastic trim” doesn't tell you which material you're buying. Check the part's marking or specification, or ask the supplier for the material name before you order. Note both surfaces your bead will touch.
Keep reading past “most plastics” on DAP's adhesion list. PVC and ABS are named there, but the same sheet calls for evaluation of five plastics. You can't treat that list as approval for every plastic part.
Before you commit to the sealant, give DAP the details of your exact part and application. If it's polycarbonate or another flagged material, ask what you need to do to evaluate compatibility.
Check what the bead will touch
Check the surface as well as the material name. If it might bleed oils, plasticizers or solvents, DAP doesn't recommend SILICONE PLUS for it. When you ask about compatibility, tell DAP about any coating or surface treatment too.
Check the joint too. The sheet limits joint width to 12.7 mm (½ inch) and calls for foam backer rod when depth exceeds 12.7 mm. It also says the sealant won't cure in totally confined spaces.
This product isn't recommended for structural glazing or continuous underwater use. If either describes the job, ask for a product specified for that application.
Don't turn one product's list into a rule for all silicone
Keep this check tied to the exact product: DAP SILICONE PLUS Advanced Window, Door & Siding 100% Silicone Sealant. If you change products, check the replacement's own sheet before carrying over the material choice.
Planning to paint over the bead? SILICONE PLUS isn't paintable. DAP directs you to paint the substrate before applying the sealant.
Resolve the material question before buying
Use the [DAP Canada technical sheet](https://www.dap.ca/media/11159/08_2021_wd_c-s_dap-silicone-plus_tdb_en_final.pdf) for the full restrictions. The supplied 2021 sheet calls for evaluation of the five flagged plastics but doesn't give a test procedure or acceptance criteria.
Open the [SILICONE PLUS product details](/silicone_plus/) when you're ready to check the product. If compatibility is still unresolved, send Cranco the plastic's exact name, the other surface, joint width and depth, and whether the joint will be indoors, outdoors or exposed to water. Ask for help confirming the choice with the manufacturer.