Home » Public Forums » GMCnet » Yellowed interior shell (Palm Beach rear bedroom/cockpit surface)
| Yellowed interior shell [message #363829] |
Wed, 05 May 2021 15:21  |
boybach
Messages: 566
Registered: December 2020
Location: Vancouver Island
Karma: 4
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Anything recommended to re-whiten or de-yellerfy the surface? I can get it done in a slow slow fashion with acetone but anything better out there?
Larry
Larry - Victoria BC -
1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses
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| [GMCnet] Re: Yellowed interior shell [message #363830 is a reply to message #363829] |
Wed, 05 May 2021 15:26  |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Clean and paint it.
Sully
Bellevue wa
On Wed, May 5, 2021 at 1:24 PM wrote:
> Anything recommended to re-whiten or de-yellerfy the surface? I can get it
> done in a slow slow fashion with acetone but anything better out there?
>
> Larry
> --
> Larry - Victoria BC -
>
> 1977 Palm Beach VIN TZE167V101295 - 39,000 miles, PO said everything
> working but forgot the word NOT. New wiper blades, New SS exhaust system ..
> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Yellowed interior shell [message #363831 is a reply to message #363829] |
Wed, 05 May 2021 16:12 |
TR 1
Messages: 348
Registered: August 2015
Location: DFW
Karma: -7
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Well.... Not sure what kind of plastic the GMC shells are... But if it is ABS, the Starwars reenactors may have you covered:
https://www.instructables.com/Restoring-yellowed-Stormtrooper-armor/
Story I read was there were some Starwars cosplay people that also happened to be chemical engineers specializing in plastics. They got together on some Starwars internet forum and actually did some chemical analysis on the yellowed storm trooper helmets(took the helmets into work and ran them through some sort of chemical analyzer)
Anyway, they supposedly came up with this method of using an oxidizer and sunlight to undo the yellowing.
Here are the Cliffs Notes:
The yellowing of ABS when exposed to Ultraviolet light is the result of a flame retardant added to the plastic during the manufacturing process. The most common of which is tetrabromobisphenol –A, or TBBP-A. When exposed to UV light the TBBP-A degrades allowing Bromine to become a free radical. The bromine forms a bond with readily available oxygen and causes the yellow color.
By irradiating the ABS with UV light in the presence of more hydrogen atoms, in the form of hydrogen peroxide, we break the bonds between the oxygen and bromine and allow the bromine to bond with the hydrogen, thus reversing the discoloration.
To me, that right there is the internet at it's finest....
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
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| [GMCnet] Re: Yellowed interior shell [message #363832 is a reply to message #363831] |
Wed, 05 May 2021 18:14 |
Rob
Messages: 651
Registered: November 2013
Location: Victoria, BC
Karma: 3
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Senior Member |
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The Vintage Apple Macintosh folks also restore their old cases using a
similar method:
https://www.youtube.com/watch?v=_ewI7nMgrB8
Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath
On 2021-05-05 2:12 p.m., Mark Sawyer wrote:
> Well.... Not sure what kind of plastic the GMC shells are... But if it is ABS, the Starwars reenactors may have you covered:
>
> https://www.instructables.com/Restoring-yellowed-Stormtrooper-armor/
>
> Story I read was there were some Starwars cosplay people that also happened to be chemical engineers specializing in plastics. They got together on
> some Starwars internet forum and actually did some chemical analysis on the yellowed storm trooper helmets(took the helmets into work and ran them
> through some sort of chemical analyzer)
>
> Anyway, they supposedly came up with this method of using an oxidizer and sunlight to undo the yellowing.
>
> Here are the Cliffs Notes:
>
> The yellowing of ABS when exposed to Ultraviolet light is the result of a flame retardant added to the plastic during the manufacturing process. The
> most common of which is tetrabromobisphenol –A, or TBBP-A. When exposed to UV light the TBBP-A degrades allowing Bromine to become a free radical.
> The bromine forms a bond with readily available oxygen and causes the yellow color.
>
> By irradiating the ABS with UV light in the presence of more hydrogen atoms, in the form of hydrogen peroxide, we break the bonds between the oxygen
> and bromine and allow the bromine to bond with the hydrogen, thus reversing the discoloration.
>
>
>
> To me, that right there is the internet at it's finest....
>
>
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Rob -
Victoria, BC -
76 Royale - Rear Twins/Dry Bath
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| Re: Yellowed interior shell [message #363837 is a reply to message #363829] |
Wed, 05 May 2021 23:49 |
boybach
Messages: 566
Registered: December 2020
Location: Vancouver Island
Karma: 4
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Senior Member |
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Well all good suggestions, thanks!
I wonder how long the UV light has to stay on ...minutes? hours? days?
Larry
Larry - Victoria BC -
1977 ex-Palm Beach "Ol' Leaky" 40,000 miles, PO said everything working but forgot the word NOT. Atwood helium fridge, water heater & furnace. SS exhaust system, Onan, Iota Converter, R134A, New fuel lines & heat exchange hoses
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| Re: [GMCnet] Re: Yellowed interior shell [message #363838 is a reply to message #363830] |
Thu, 06 May 2021 00:45 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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sgltrac wrote on Wed, 05 May 2021 15:26Clean and paint it.
Sully
Bellevue wa
X2.
I did mime about 15 years ago with rattle can paint for plastic from Menards and it still looks great.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| [GMCnet] Re: Yellowed interior shell [message #363839 is a reply to message #363838] |
Thu, 06 May 2021 05:21 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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X3
About 20 years ago there was one paint renowned for use on plastic. I
don't recall the name and can't find it online now, but there are a LOT of
brands explicitly for plastics now. Mine all look, AFAIK, just like they
did an hour after I re-installed them. I think unpainted they'd be
yellowed again.
Ken H.
On Thu, May 6, 2021 at 1:45 AM Ken Burton wrote:
> sgltrac wrote on Wed, 05 May 2021 15:26
>> Clean and paint it.
>>
>> Sully
>> Bellevue wa
>
> X2.
>
> I did mime about 15 years ago with rattle can paint for plastic from
> Menards and it still looks great.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: Yellowed interior shell [message #363840 is a reply to message #363829] |
Thu, 06 May 2021 09:13 |
TR 1
Messages: 348
Registered: August 2015
Location: DFW
Karma: -7
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Senior Member |
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I've used SEM plastic paint in the past with good results...
I believe they make an adhesion promoter as well that you can wipe or spray on the plastic before applying paint that will kind soften up the plastic which apparently helps the paint stick...
I would consider this a mandatory step, unless you want to do the whole panel again when it starts to flake off in a few months...
Also, before using the adhesion promoter, you need to clean the heck out of the plastic... Any silicone (from armor all or whatever), grease, oil etc. and the paint will flake. I believe SEM makes a product for this too.
Painting plastic can be hit or miss... But I've found if you follow the whole system for whatever brand you choose, (Cleaner, Prep, Adhesion Promoter, etc.) you have the best chance of the paint not flaking down the road....
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
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| [GMCnet] Re: Yellowed interior shell [message #363843 is a reply to message #363839] |
Thu, 06 May 2021 09:07 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Senior Member |
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Over the last 20 years on the coach interiors that I have done I used Krylov Fusion paint for plastic with excellent results. Comes in many colors and easy to apply. Just a good cleaning of the plastic and a light rub with 204 paper. Did my rear cap and any other misc pieces in our 77 during the interior restoration. Available at big box stores and Ace Hardware.
J.R. Wright
GMC Great Laker MHC
GMCGL Tech Editor
GMC Eastern States Charter Member
GMCMI
78 GMC Buskirk 29.5’ Stretch
75 GMC Avion (Under Reconstruction)
Michigan
> On May 6, 2021, at 6:21 AM, Ken Henderson wrote:
>
> X3
>
> About 20 years ago there was one paint renowned for use on plastic. I
> don't recall the name and can't find it online now, but there are a LOT of
> brands explicitly for plastics now. Mine all look, AFAIK, just like they
> did an hour after I re-installed them. I think unpainted they'd be
> yellowed again.
>
> Ken H.
>
>
> On Thu, May 6, 2021 at 1:45 AM Ken Burton wrote:
>
>> sgltrac wrote on Wed, 05 May 2021 15:26
>>> Clean and paint it.
>>>
>>> Sully
>>> Bellevue wa
>>
>> X2.
>>
>> I did mime about 15 years ago with rattle can paint for plastic from
>> Menards and it still looks great.
>> --
>> Ken Burton - N9KB
>> 76 Palm Beach
>> Hebron, Indiana
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
_______________________________________________
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| [GMCnet] Re: Yellowed interior shell [message #363846 is a reply to message #363840] |
Thu, 06 May 2021 09:48 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Sanding should not be necessary unless you need to correct surface flaws.
Scrub the plastics with a strong water based cleaner and red scotchbrite
pads, rinse well with water, dry and spray.
Sully
Bellevue wa
On Thu, May 6, 2021 at 7:14 AM Mark Sawyer wrote:
> I've used SEM plastic paint in the past with good results...
>
> I believe they make an adhesion promoter as well that you can wipe or
> spray on the plastic before applying paint that will kind soften up the
> plastic
> which apparently helps the paint stick...
>
> I would consider this a mandatory step, unless you want to do the whole
> panel again when it starts to flake off in a few months...
>
> Also, before using the adhesion promoter, you need to clean the heck out
> of the plastic... Any silicone (from armor all or whatever), grease, oil
> etc. and the paint will flake. I believe SEM makes a product for this too.
>
> Painting plastic can be hit or miss... But I've found if you follow the
> whole system for whatever brand you choose, (Cleaner, Prep, Adhesion
> Promoter, etc.) you have the best chance of the paint not flaking down the
> road....
>
>
> --
> Mark S. '73 Painted Desert,
> Manny 1 Ton Front End,
> Howell Injection,
> Leigh Harrison 4bag and Rear Brakes,
> Fort Worth, TX
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Yellowed interior shell [message #363847 is a reply to message #363840] |
Thu, 06 May 2021 10:25 |
 |
Richard RV
Messages: 631
Registered: July 2012
Location: Full-timer for 12 years, ...
Karma: -17
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Senior Member |
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Most paint manufacturers now have paint formulations with primer and paint in one, both for house paint and spray paint, which makes painting, touch-ups and clean-up a lot easier.
I've used Rustoleum Universal Paint and Primer in One both inside and outside the coach. Inside I just clean and degrease the plastic and spray away. On the outside I wiped down the roof with acetone and sprayed. It's tough stuff. You can scrub away on it and use regular household cleaners with no worries. It's also a lot cheaper and more readily available than automotive brand specialty paints like SEM.
Richard
'77 Birchaven TZE...777;
'76 Palm Beach under construction;
‘76 Edgemont waiting its turn
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| [GMCnet] Re: Yellowed interior shell [message #363848 is a reply to message #363846] |
Thu, 06 May 2021 10:00 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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What Sully said!!. It is really no big deal. Most important step is to
clean all the cigarette smoke, cooking grease, etc from the surface. One
thing to keep in mind. Most, if not all, sheet moulded plastics are LOADED
with release agents to make them easy to get out of the molds. Aggressive
sanding will expose more of them to the surface. PAINT WILL NOT ADHERE TO
MOLD RELEASE AGENTS. SO, easy on the sanding here. All I got!
Jim Hupy
Salem, Oregon
On Thu, May 6, 2021, 7:48 AM Todd Sullivan wrote:
> Sanding should not be necessary unless you need to correct surface flaws.
> Scrub the plastics with a strong water based cleaner and red scotchbrite
> pads, rinse well with water, dry and spray.
>
> Sully
> Bellevue wa
>
> On Thu, May 6, 2021 at 7:14 AM Mark Sawyer
> wrote:
>
>> I've used SEM plastic paint in the past with good results...
>>
>> I believe they make an adhesion promoter as well that you can wipe or
>> spray on the plastic before applying paint that will kind soften up the
>> plastic
>> which apparently helps the paint stick...
>>
>> I would consider this a mandatory step, unless you want to do the whole
>> panel again when it starts to flake off in a few months...
>>
>> Also, before using the adhesion promoter, you need to clean the heck out
>> of the plastic... Any silicone (from armor all or whatever), grease, oil
>> etc. and the paint will flake. I believe SEM makes a product for this
> too.
>>
>> Painting plastic can be hit or miss... But I've found if you follow the
>> whole system for whatever brand you choose, (Cleaner, Prep, Adhesion
>> Promoter, etc.) you have the best chance of the paint not flaking down
> the
>> road....
>>
>>
>> --
>> Mark S. '73 Painted Desert,
>> Manny 1 Ton Front End,
>> Howell Injection,
>> Leigh Harrison 4bag and Rear Brakes,
>> Fort Worth, TX
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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| Re: Yellowed interior shell [message #363890 is a reply to message #363829] |
Sat, 08 May 2021 22:54 |
GatsbysCruise
Messages: 261
Registered: January 2017
Location: Waukegan, Illinois
Karma: 3
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Senior Member |
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Back in the days when monitors were made of that white plastic, with aging the white plastic would turn to yellow
and look really really old.
They found that wiping the plastic down with hydrogen peroxide helped restore the white color again.
I never did this so I don't know how abrasive or otherwise the hydrogen peroxide is to the plastic
so try in on a spot that is not obviously visible.
let us know how it works out.
GatsbysCruise. \
74GMC260 Former Glacier Model style. \
Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS FASTER THAN YOUR HONOR ROLL STUDENT \ WindowsXP-Win7-Win8.1-UBUNTU STUDIO - UBUNTU VOYAGER - Berzin Auto Center
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| Re: Yellowed interior shell [message #363907 is a reply to message #363829] |
Sun, 09 May 2021 13:13 |
MikeB
Messages: 133
Registered: December 2018
Location: South Bama
Karma: 1
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Senior Member |
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I restored a 1949 stove that had plastic end caps on chrome handles. The end caps were disgustingly yellow from 70 years of grease and smoke. I dropped them in a cup of hot water and oxyclean detergent. Cleaned and whitened like new after 6 hours. Did not effect texture of the plastic. Not sure how you’d do a large ceiling cap. Also not sure how long it would take to return to yellow. It’s been a year of use with no yellowing.
M Beam
75’ Avion
TBI EBL , 3.70 LSD and other stuff
Zuki Sidekick,
Dozier Al
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