Friday, April 30, 2010

Purging Tip of the Week: #11

Titanium dioxide (TiO2) presents one of the more difficult color-removal challenges, especially when present at high loadings. When faced with the need to remove a white material carrying a high level of this pigment, an effective pre-flush is very important.

Use a clean, natural material that is stiffer (i.e., higher in viscosity) than the pigmented production material (regrind is fine) and then flush until – in your judgment – the bulk of the white color has been removed. Then finish up the job with a good purging compound. And remember to run the screw empty between materials so that mixing dilution doesn't hamper effectiveness.

Thursday, April 29, 2010

Are We a Leading Indicator?

Last evening on National Public Radio's Marketplace program, there was a brief story proximately occasioned by Dow's announcement of gratifying first quarter profits. (Here's a link to the transcript.)

About the good news from Midland, the story suggested: "The reason? Just one word: plastics," and went on to note the following:

If you want to see signs the economy is bouncing back, look no farther than plastic.

George Van Horn is a manufacturing analyst at IBIS World Industry Research. He says Dow Chemical's earnings are like a broad economic indicator.

"Because plastics find their way into every nook and cranny, really, of the economy."

So, the Mainstream Business Media is looking to our humble industry as an indicator that the industrial recovery is well underway. That's nice.

Monday, April 19, 2010

Purging Tip of the Week: #10

Black specks present in significant numbers (at start-up or during production) almost certainly indicate the existence of a substantial amount of degraded material built up inside the system. Specks usually do not emerge in numbers until the contamination is quite advanced. At that point, the likelihood that any purging compound can remove all of the carbon build-up is rather small.

This isn't what you want to hear, but - you need to get back to a clean machine by tearing down one more time. Thereafter, purge regularly (e.g., at each shutdown) to prevent recurrence of carbon buildup.

Friday, April 16, 2010

This is Refreshing!

Now comes Ms. Patty Fisher, a columnist for the San Jose Mercury News, who set out lately to write the usual treatise on the virtues of life without plastic. This because the local county solons had begun the move toward banning plastic bags. But a funny thing happened. Ms. Fisher seems to be an intellectually honest journalist, so she felt it proper to try telling both sides of the story.

The resulting column focuses not so much on the virtue of saving us all from death-by-plastic, as on the intriguing arguments found at The web site is sponsored by an industry group commercially interested in plastic bags, and is guided by Mr. Stephen Joseph, who turns out not to be your generic Industry Advocate from central casting. He's actually an environmentalist with a good record on "green" issues who happens to believe that plastic bags have been subjected to an unfair rap - and he has the arguments to prove it.

Rather than replicating Mr. Joseph's information here, I'll just suggest that you click on the link to his site and enjoy some fresh thinking on the plastic bag question. It's especially vital for you to do so if you happen to reside in one of the increasingly common jurisdictions where efforts are in process to ban plastic single-use bags. It will give you the arguments you'll need to resist the ban advocates with their own logic.

And, kudos to the Mercury News' Ms. Fisher for her open mindedness and willingness to speak truth rather than parroting the conventional wisdom of the day. She still believes that the days of single-use bags are numbered, but she declines to condemn plastic bags reflexively - good for her!

Thursday, April 15, 2010

Purging Tip of the Week: #9

If you are losing productivity at start-up on Monday morning because of black specks, this is not the time to bring out the purging compound! The time to purge is at shutdown! It’s always a better approach to avoid the formation of carbon rather than attempt to address it after it’s formed. A purging compound is best viewed as a maintenance tool and not as a fire extinguisher.

If the situation has been allowed to deteriorate to the point where there's a sizable inventory of degraded material in the machine, there is really no practical alternative to tearing down the system and cleaning the components by hand. Thereafter, you can make effective use of purging compounds to avoid finding yourself in the same situation in the future.

Monday, April 5, 2010

Purging Tip of the Week: #8

On a dark-to-light color change, when emptying the system of the dark colored production resin be certain that all of the dark material is removed from the hopper and throat areas. It only takes a few pellets of color concentrate that hang up in or near the throat and then fall into the throat opening late in the purge to cause unsatisfactory results.

Thursday, April 1, 2010

Apparently Not an April Fool's Prank

For a while there I thought that the April 1st dateline on Bryan Walsh's piece for Time titled The Perils of Plastic was just a joke. Unfortunately, it appears that we are supposed to take this seriously.

You may want to go ahead and read the piece. Try to stay calm. It's a recycling of the known concerns about BPA and phthalates, mixed with heavy breathing and lots of "can have" and "may cause" and "could have" and "might". Some of the technical inaccuracies would be worth a laugh if it weren't for the fact that the lay readership will take the fear-mongering at face value.

Naturally we need to take concerns about the environmental impacts of our chemistries seriously. But the sort of alarmist journalism produced this morning by Time, devoid of logic and balance, certainly does not contribute to constructive discussion.