So i have been doing some overlays recently just to bring some money into the “composites fund”
Ive done a few now (20-30) and im very confident with it but…
recently, when im letting my overcoat of resin cure, its staying tacky for like 3-4 days at 25+ dec C…
The mixture is always spot on! and i degas too…
Im at a loss now because i have some very exspensive parts sitting here waiting to be finished but the resin is still tacky as hell
Any ideas?
Did you you recently switch to a new batch of resin or are you using resin that is very old? I’ve had resin stay tacky because I didn’t mix it correctly but I’ve also had resin stay tacky because it had been sitting in a cabinet for over a decade.
Brand new resin from supplier, i thought it was because of insufficient mixing but its not the first time recently with this resin…
I was thinking, maybe its humidity in the room… so im gonna do another test today with a dehumidifier and see how that goes… if then it fails… i am definatly gonna blame the resin lol
what type of resin is it? If it is a VE or PE it proabaly is a laminating resin which will always have a tack to it unless you has a special wax to the mix. They are designed to remain tacky so you get a better secondary bond. You might find using a different catalyst you will get it to cure better, there many to choose form, I would suggest first looking at the data sheet to see the specific one that is recommended.
cheers hojo, but its epoxy :S
which epoxy is it, and what are the specs?
its this one
http://www.easycomposites.co.uk/products/epoxy-resin/epoxy-laminating-resin.aspx
Specification
Property Units Resin Hardener Combined Material - Epoxy Resin Formulated Amine Epoxy Appearance - Clear Liquid Amber Liquid Clear Liquid Viscosity @ 20°C mPa.s 12000 - 15000 120-220 1000 - 1400 Density @ 20°C g/cm³ 1.08 - 1.20 0.90 - 1.10 1.05 - 1.15 Pot Life & Cure Times
Pot-Life @ 25°C Demould Time @ 25°C Demould Time @ 50°C Demould Time @ 65°C 30-50 mins 8-14hrs 4-8hrs 2-3hrs Cured Properties
These properties describe the resin only. The mechanical properties of a reinforced composite would be considerably different.
Hardness
(Shore D) Linear Shrinkage Tensile Strength
MPa Elongation at Break Flexural Strength
MPa Flexural Modulus
MPa Heat Distortion Temperature
°C 85-90 0.50 35.0-40.0 7.0-9.0 56.0-62.0 1000-155 76-80
Hmmm, no idea what is happening. It could be oxidation of the curing agent, which gives a yellow waxy appearance. But then again a 100:50 ratio suggests a polyamine curing agent, which would never reach 80 degrees C HDT.
They made a mistake on their (fantastic!) website. is the viscosity of the resin 1200-1500 (as per datasheet) or 12000-15000, which would be very thick. In cold weather it would be almost impossible to get the stuff to leave the container. Which of the 2 is it?