Can Eastman Spectar™ copolyester be solvent bonded with good results? Which solvents and techniques are recommended?

Yes! Eastman Spectar™ copolyester can be solvent bonded with good results. Technique is very important. For those familiar with solvent bonding acrylic, similar techniques are still applicable—we recommend a few modifications for best results.

Solvent bonding is a common technique used for joining two plastic parts together. A solvent mixture is applied at the bond joint to dissolve the surface of the two materials. As it evaporates, a strong plastic-to-plastic bond results. Solvent bonding is an effective method for joining sheets made of Spectar.

Here are a few useful tips:

  • Parts should be properly machined and edges adequately prepped.
  • Make smooth cuts to ensure a tight fit along the entire edge of the bonding area.
  • If using a router bit, we recommend using a straight flute.
  • Use a fixture to align or hold parts securely.
  • Apply only enough solvent to cover the entire joint without excess. Applying too much solvent may cause the joint to haze. Note SINC (solvent-induced crystallization) may occur if too much solvent is used.
  • Make sure the solvents are within their use-by date. Protect solvents from absorbing moisture. Old solvents or those used in high-humidity areas may result in weak bonds.
  • Use a syringe with a 22-gauge needle or smaller to enhance capillary action.
  • Apply slight pressure to parts to eliminate bubbles at the joint.
Spectar- Solvent Bonding

Allow sufficient time for curing:

  • Green time = 60–90 seconds (amount of time required before a part can be moved after bonding)
  • “Strong to the touch” = 8–10 minutes (amount of time required before additional parts can be added)
  • Complete bond time = 24 hours (amount of time it takes for a bond to completely)

Typical solvents used are methyl ethyl ketone (MEK), tetrahydrofuran (THF), cyclohexanone, methylene chloride, ethyl acetate, and blends of MEK and methylene chloride.

View the video to see solvent bonding in action.

Solvent bonding video


For additional tips, download our Fabrication Guide.