Color Issues......

[Joel JS]

Hello everyone,

We have color issues on different jobs that are quite irritating... , Just for example we get in a natural ABS, use a color auger, or gravimetic mixer, to mix in at 2%... then there's a lot of possible color issues which we usually, eventually, overcome,, such as: 1. too light/too dark... 2. looks different than the plaque/ "gold standard", or 3. color streaks.

My question is this...... , if we pay more and go to a pre-compounded colored resin, is it safe to assume no more color issues?

Happy Thanksgiving!

thx! Joel

[rickbatey]

Joel,
Pre-colored may reduce your troubles but they rarely go completely away long term. I think you hav an issue with the carrier resin of your color and perhaps something is wrong with your color settings calculation or the feeders themselves. Also what are your barrel settings, screw rpm and back pressure ? Maybe these are off and causing the issue.
I say the issue never goes away because I’ve seen issues with pre-colored resin being too red or green when running black.
BR,
Rick

[brentb]

Rare are the times when I don't agree 100% with "Reb Rick", but compounded or pre-colored resin will all but eliminate your issues,as there will be no carrier resin,nor dosing issues.

KOM
brent

[Joel JS]

Ok, Thanks..... I appreciate your feedback! Joel

[chrisprocess]

Hi Joel JS,

In my experience colors can be very tricky. In many ways subjective - their appearance can easily change based on surface finish, wall thickness, and type of lighting the observer is viewing. Not to mention humans see color slightly different from person to person.

Pre-colored will most likely solve your issues of consistency, but it'll cost more $$.

Here's a few things that have helped me in the past:

Establish an acceptable color window (high and low) - have customer/quality or whoever sign off on it
Increase mix ratio from 2% to 4% (w/ lighter colorant) - allows greater number of colorant pellets for a better mix
Increase back pressure - allows more screw RPM's during dosage for improved mix
Use less barrel % during dosage - increases residence time, allowing more mix time
Contact colorant manufacture - ask for a tighter colorant processing window, as colorants can easily change lot to lot
Static in the colorant can build up colorant near feed throat
Use a gravimeter feeder (I try to stay away from colorant augers)

Check out this photo below of the same colorant, but from different lot #'s
Samples on the left are much lighter than the samples on the right. Take a look at the colorant pellets sizes - which in this case was root cause.


For some just compounding the color is much easier..
Good luck!

Chris