steven's and white pass update

[Mike Peplinski]

Would one of you plastics engineers explain the phenomenon of heating the plastic to get the color back. My understanding is that when you stress the plastic by stretching or bending it you disrupt the plastic polymers which contain the colorant and expose the natural plastic, which is a white color. Heating relaxes the stretch, or grain and the colorant again appears. Is this a good idea or does it weaken the plastic? Since molded plastic parts are made by heating the plastic, I don't like to apply more heat to get the color back and risk returning the nice molded parts to their native, liquid state.

[cruiserjones@sbcglobal.net]

Asking to talk to an engineer about this, you must have plenty of time on your hands! From a "street level" response, I've done it, no problems, it won't solve all the color issues, but does help. It also won't change all the discolor all the time. Give it a whirl, there's nothing on the bike but the fairing where strength is a big issue, I've done parts of the fairing and side covers, no problems. You're not gonna heat the whole piece.....wait a minute, maybe in the oven??? Hmmmmm, "honey, why don't you go look at the new couch you like for a couple hours...." "Texx" Jones

----- Original Message ----- From: "Mike Peplinski" To: DSN_klr650@yahoogroups.com> Sent: Tuesday, April 04, 2006 7:38 AM Subject: [DSN_KLR650] Color change/'splain it to me > Would one of you plastics engineers explain the phenomenon of heating the > plastic to get the color back. My understanding is that when you stress > the > plastic by stretching or bending it you disrupt the plastic polymers which > contain the colorant and expose the natural plastic, which is a white > color. > Heating relaxes the stretch, or grain and the colorant again appears. Is > this a good idea or does it weaken the plastic? Since molded plastic parts > are made by heating the plastic, I don't like to apply more heat to get > the > color back and risk returning the nice molded parts to their native, > liquid > state. > > > > > Archive Quicksearch at: > http://www.angelfire.com/ut/moab/klr650_data_search.html > List sponsored by Dual Sport News at: www.dualsportnews.com > List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html > Member Map at: http://www.frappr.com/dsnklr650 > Yahoo! Groups Links > > > > > >

[Streetfighter]

Heating the plastic to return the color is used by all the plastics companies in the finishing process before you get the part anyway. It doesn't hurt the part if it's not heated to liquid again. A hair dryer may work on thin plastic but a "heat gun" if used briefly is best. It's like a high powered hair dryer. But it's never done in excess where the plastic begins to liquefy. Just a lot of heat briefly does the trick. As for the technical side - not all plastics use white as a colorant. It depends on the final color desired and the chemical compounds used. Some PolyVinylChlorides (PVC) don't react well to heat as they become brittle. ABS reacts well as does Polyester. When the parts are made, they usually (99.99% of the time) have some flash or excess material on the outside edges which need to be hand trimmed. The trimming of this flash can be removed several ways depending on a bunch of things. Sometimes they use a heat gun to literally curl.melt it away and then run a deburring tool over the affected area. Sometimes they use an iron, sometimes they don't heat it at all and just run a deburring tool over it. It all depends. Other anomalies such as "warping", "sinks" and "knit lines" can be repaired by using heat. Some manufacturers actually give the operators a torch to wave over the affected areas to repair the parts. They also use heat when the outside finish isn't "per spec". The heat can make the surface area shiny and if applied by an experienced operator you'd think it came out of the mold that way. Motorcycle body parts? Go ahead and heat it - briefly. Don't use this method on such parts as the plastic controls though as they have strengthening fillers such as fiberglass which doesn't react the same way the plastic does. That's why aged control housings look the way they do because the UV rays affect the plastic and NOT the glass making them appear to "sparkle" after years in the sun. Geoff- www.oldrice.com

----- Original Message ----- From: "Mike Peplinski" To: Sent: Tuesday, April 04, 2006 8:38 AM Subject: [DSN_KLR650] Color change/'splain it to me Would one of you plastics engineers explain the phenomenon of heating the plastic to get the color back. My understanding is that when you stress the plastic by stretching or bending it you disrupt the plastic polymers which contain the colorant and expose the natural plastic, which is a white color. Heating relaxes the stretch, or grain and the colorant again appears. Is this a good idea or does it weaken the plastic? Since molded plastic parts are made by heating the plastic, I don't like to apply more heat to get the color back and risk returning the nice molded parts to their native, liquid state. Archive Quicksearch at: http://www.angelfire.com/ut/moab/klr650_data_search.html List sponsored by Dual Sport News at: www.dualsportnews.com List FAQ courtesy of Chris Krok at: www.bigcee.com/klr650faq.html Member Map at: http://www.frappr.com/dsnklr650 Yahoo! Groups Links

[JRC]

I hadn't heard of using heat to restore the color before. My best technical guess is that over time, the polymers used in the part undergo UV degradation, with a resultant loss of gloss. Heating the suface softens a miscroscopic layer of the part, which then undergoes reflow, and gets all smooth and shiny. Glossy surfaces have deeper color than matte surfaces (reasons I won't go into her, but think of waxing a car. JRC A13 '01 LC1500

[John Kokola]

Thanks Geoff! --John Kokola Streetfighter wrote:

>Don't use this method >on such parts as the plastic controls though as they have strengthening >fillers such as fiberglass which doesn't react the same way the plastic >does. That's why aged control housings look the way they do because the UV >rays affect the plastic and NOT the glass making them appear to "sparkle" >after years in the sun. >

[Mike Frey]

Geoff sounds like a voice of experience! He used some technical terms that are common only in the plastics industry. The statement When the parts are made, they usually (99.99% of the time) have some flash or excess material on the outside edges which need to be hand trimmed might be applicable in China. If USA manufacturers are trimming that high a percentage of parts (too much manual labor), they aren't long for this world, but I digress . The white deposit on the plastic (they're polypropylene) body parts of our KLRs is the result of solar (UV) degradation, which oxidizes the surface of the plastic. A loose analogy is plastic rust . Left in the sun too long, the color will fade, the polypropylene will degrade the whole way through, and the entire structure will severely weaken to the point that you could crumble it with your bare hands. A carefully applied torch or heat gun will restore the surface as described except in those severe cases. You could sand it, but that's time consuming and very difficult to get back to the smooth, semi-gloss of the original finish. Note: polypropylene has a melting point of 320 degrees F, so if you get JUST the surface of your fender to that temperature, you'll achieve results. DON T allow the whole item to get that hot I wouldn't even trust it in an oven at 200 degrees - it will warp when it cools back down again. Pledge furniture wax, described on this list before, also improves the appearance. Any protectant with UV light blocking agents in it, including Armor-All, will preserve the surface better than not doing anything at all. Mike A18 still very red www.integrityplastics.com http://www.integrityplastics.com/>

[Streetfighter]

Actually, these parts I'm familiar with are all automotive parts. Everything from inner fender wells to outside door handles and interior trim pieces. And in Mexico they seem to do it right - more consistently than they do here in Detroit. Here, you get what you pay for so the quality isn't that great and requires a lot of rework. If rework is required at all in Mexico, it's automated to the point where it becomes part of the process. Yeah, I've dabbled a bit in a lot of things. Geoff- www.oldrice.com www.keyplastics.com www.mayco-mi.com www.plastech.com www.compositeshop.com www.lear.com www.alpsautomotive.com www.autoliv.com www.trw.com I could go on...

----- Original Message ----- From: "Mike Frey" Geoff sounds like a voice of experience! He used some technical terms that are common only in the plastics industry. The statement When the parts are made, they usually (99.99% of the time) have some flash or excess material on the outside edges which need to be hand trimmed might be applicable in China. If USA manufacturers are trimming that high a percentage of parts (too much manual labor), they aren't long for this world, but I digress . .......snipped.......

[Chris Neil]

This past week, I had the pleasure of hitting both of these passes. Steven's was amazing. Snow packed 10-15 ft high. Very Impressive and no where near time for trail riding. White pass was extremely picturesque. Snowline around 3000 ft was absolutely amazing to see. Just like a post card. Heated grips from Dual star allowed for such an adventure. I imagine it will be quite sometime before Chinook and Cayuse passes will open. http://www.wsdot.wa.gov/traffic/passes/cayuse/