How to Glue Fiberglass to Plastic
It will be simple to glue fiberglass to plastic or vice-versa using epoxy resin, silicone adhesive, and super glue. Epoxy resin and silicone are excellent choices for long-term adhesion but require longer curing times to complete this task. Super glue is only recommended when there isn’t the luxury of time involved.
When choosing which glue to use only takes some careful attention to which adhesive works best for fiberglass and plastics strengths and weaknesses. In addition, it will be necessary to clamp or secure two pieces being glued together if these surfaces are not totally flat.
This guide will provide three types of adhesives that will all have advantages and disadvantages for why they are best to use. Depending on the application and amount of time that is allowed, this will help determine which glue is better and why.
Which Glue Should You Use For Fiberglass To Plastic?
The best glue for fiberglass and wood is also the best for most other fiberglass projects – Epoxy resin. Here are three of the best glues to use on fiberglass and plastic:
Epoxy Resin
2-part epoxy is an excellent example of adhesive that’s used when two rigid surfaces need to be glued together. Because epoxy resin comes in a 2-part kit, the curing times will affect the total adhesion, so more time is needed when using epoxy resin. Gluing fiberglass to plastic will need to have continual contact added between these two surfaces until the curing is complete.
The bond that is completed between fiberglass and plastic is much higher when there is light preparation before the fiberglass and plastic are glued together. The total working time of epoxy resin depends on the curing time shown for each brand. It can take anywhere from 5 minutes for quick cure epoxy to 1-hour for long cure epoxies. A total cure can take up to a whole day for post-curing.
Silicone Glue
There is silicone caulking and then there is a silicone adhesive. These two types of silicone are not the same, so it’s better to look for silicone adhesive. This adhesive is a one-component version that comes in a squeeze tube or in a rounded tube just like regular caulking does. These tubes require a caulking gun to get the glue out. Many of these silicone adhesives are transparent and dry totally clear when completely cured.
The bonding with silicone is ideal for gluing fiberglass to plastic with very little preparation or clamping involved. The curing time will take up to a whole day for a total cure, yet the initial bonding time only takes as little as a couple of hours.
Superglue
Super glue is a quick fix that is fine for gluing fiberglass to plastic but there will be some preparation that helps to make the adhesion better. Since super glue is pressure-sensitive glue, the initial adhesion is perfect for instant bonding. There is a post-cure that is best for anything long-term and does need a few minutes to gain full strength. It’s better to use super glue where there is little flexing involved since the adhesive quality can break if flexed.
This is the only glue that can be removed using acetone if there was a mistake made while gluing fiberglass to plastic. The surfaces can be both cleaned and prepped again to get a better fit so each piece will lay flat against the other.
How To Prepare Fiberglass To Plastic
The first step is to sand both surfaces to have an ideally flat area that is being glued. Use a sanding block with 250-300 grit sandpaper that allows enough bite on both sides that are being glued. Fiberglass may have texture from the cloth or chopped matt which needs to be as flat as possible unless there was a gel coat applied. It’s also a good idea to clean off each surface with acetone or isopropyl alcohol and wipe dry using a paper towel.
How To Apply Glue To Fiberglass To Plastic
Both epoxy resin and silicone glue are best applied using a pop stick or something flat to apply a thin coating on one side only. It’s not necessary to apply it to both pieces since this can cause spillover when the two pieces are pressed together. Super glue is applied to a horizontal surface area that is being glued. Only add one or two drops depending on the size of the piece being glued.
Lay the other piece on top of the superglue and allow the liquid to spread out without pushing it. Only when the two pieces are laying flat is when it will be advised to apply pressure to start the adhesion. Equal pressure is better rather than pushing in the middle or from one side. Always wear gloves when applying any glue to each surface.
How To Cure Glue Fiberglass To Plastic Glue
Super glue is an instant cure when pressure is applied and doesn’t need clamping at all. The post-cure does take a couple of hours to reach full strength as the super glue begins to solidify. Silicone and epoxy will need clamping or something that places weight on the two pieces that are being glued. For objects that cannot be laid horizontally, anything vertical will do fine by adding masking tape to secure the pieces along their edges.
Masking tape will prevent a piece from sliding down due to gravity if clamps cannot be used. Paperclips and cloth pins are good for small objects whereas light-duty spring-loaded clamps are best for larger objects. Epoxy and silicone will take up to 24 hours to completely dry.
Which Is The Best Glue To Use And Why?
Epoxy resin and silicone are the best glues when adequate time is allowed for drying and curing. Silicone adhesive offers better flex than epoxy if there are parts that require some slight movement or bending. Super glue, is good when objects need to be glued in the shortest time possible. Super glue is not permanent and can weaken or pop loose if there is any flexing but is fine when there is a last-minute fix that’s required.
