CA's - Thin, Thick or Very Thick? Which to use for what?

 

Question: What is the difference between the various thicknesses of CA's? Some are thin like water, others are thick like syrup or molasses. Which is to be used for what? 

Short Answer:

- Thin CA offers the fastest cure, can be applied after parts are assembled, parts MUST fit well, and thin CA is reasonably tolerant of different wood types

- Thick CA offers fast cure, must be applied to the parts prior to assembly, some roughness of fit is OK and thick CA is very tolerant of different wood types.

- Very Thick CA offers a slower cure, must be applied to parts prior to assembly, can be applied to parts that fit poorly, can be used like a white or aliphatic glue and very thick CA is tolerant of different wood types.

Better Answer:

1) Thin... almost like water (typical viscosity 5 centipois).

- works well on pure woods and plastics (except Teflon, Delrin or Nylon) that fit very well. There should not be a gap between the parts. The wood should not be pitchy or laminated like plywood. - does not work well on pitchy wood, dirty parts, rough fitting parts or parts that are extremely porous. - cure time is almost instant, in the order of seconds - parts should be assembled first and the adhesive wicked into the joint externally. The adhesive will penetrate many millimetres and up to a centimetre into the joint area. - great for assembling open frameworks like model airplane wings that can be fitted together, pinned into position and then glued together when ready. Just apply a drop to each joint area, wait a few moments and you can remove pins etc and you are done! - do NOT use thin CA with CA accelerators. - typical brand names, ZAP with a Pink Label, VCA with a Red Label.

2) Thick sometimes called Medium... like warm syrup (typical viscosity 100 centipois).

- works well on all woods and plastics (except Teflon, Delrin or Nylon) that fit reasonably well. Parts should fit well but will tolerate some roughness of fit. - Tolerant of pitches, veneers and plywoods. Works well on hardwoods. Tolerates some porosity of substrates. - cure time is related to tightness of fit. Generally cures in 10 seconds when parts fit well. Up to a minute for rough joints. May take even longer to cure in open puddles. In all cases, application of accelerators like Zip Kicker and VCA Velocity speed up cure. - parts should be trial fitted first to ensure a good fit. Parts should then be separated and thick CA applied to one surface like white glue. the parts then can be fitted and secured in place to allow the adhesive to cure.  The adhesive will penetrate slightly into the substrates but not enough to allow for wicking after the parts have been assembled. External application will produce a fillet along the joint that does add strength to the joint but should not be the main adhesive joint. - great for assembling model airplane fuselages, hardwood bearers, plywood components, boats, veneers and most plastics. Probably the best all round choice if you must choose only one adhesive. - recommended for use with CA accelerators. - typical brand names, ZAP-A-GAP with a Green Label, VCA with a Green Label.

3) Very Thick... like white glue or aliphatic glue (typical viscosity 700 centipois).

- works well on all woods and plastics (except Teflon, Delrin or Nylon). Parts should fit but will tolerate considerable roughness of fit and gaps of up to a millimetre. - Tolerant of pitches, veneers and plywoods. Works well on hardwoods. Tolerates considerable porosity of substrates. - cure time is related to tightness of fit. Generally cures in 20 seconds when parts fit well. Up to a couple of minutes for rough joints. Will take longer to cure in open puddles. In all cases, application of accelerators like Zip Kicker and VCA Velocity speed up cure. - parts should be trial fitted first to ensure a good fit. Parts should then be separated and very thick CA applied to one surface like white glue. The parts then can be fitted and secured in place to allow the adhesive to cure. The adhesive will penetrate only slightly into the substrates and not enough to allow for wicking after the parts have been assembled. External application will produce a fillet along the joint that does add strength to the joint but should not be the main adhesive joint. - great for assembling model airplane fuselages, hardwood bearers, plywood components, boats, veneers etc. Great if you want the speed of a CA while using assembly methods applicable to white glue. - strongly recommended for use with accelerators. - typical brand names, SLOW ZAP with a Yellow Label, VCA with a Blue Label.