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Old 12-24-2009, 05:52 PM
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Anyone ever refinished an Acrylic top?

I have a 1994 corvette that has the factory acrylic top. Most people call it a Glass top. But it is not glass, it is acrylic like lexan.

The top is not cracked. But has spider cracks across the whole outside from sun damage. It looks like it has an automotive clear sprayed over it, and the clear is dry and cracked.
A new rebuilt top is around $1000. I would like to save this top myself If possible.
My plan is to wet sand it starting with 400 and end with 1500 to remove all the spider cracks. But After I remove the spider cracks should I spray a clear coat over it, Or should I try to polish the acrylic?

I talked to one person that refinished his in the past. He sanded it and sprayed clear over it. It looked good from the outside. But when you got in the car and looked out, You could see sanding marks big time from the use of an orbital sander. The guy said he started sanding it by hand and found the factory clear coat to be much to thick and hard to remove by hand and ended up using an orbital sander. If that be the case, Do you believe I could use 400 grit on a orbital to remove the cracked coating, and after it is removed hand sand it starting with 400 to remove the swirl marks?

Im open to suggestions. Ive never had to refinish clear plastic before other then buffing headlights.

Thanks

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Old 12-24-2009, 07:03 PM
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What about a plastic safe paint stripper,If there is such a thing,then reclear?
Shane
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Old 12-24-2009, 07:05 PM
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spider webbing.....

Hi,as ive been TOLD.the reason for the webbing is that the top has been cleaned with WINDEX,and it pulled the oils out of the top.what i would do,is use 400 grit on a JITTERBUG, NOT a DA, with PLENTY of water,and change paper frequently.then go to 600 grit,then 1000,or more fine if it looks like you need it, keep looking from bottom (inside) of top,when webbing is GONE,then buff with the 2 grits of compound,then put about 3 or 4 coats of a good paste wax on the tops. let us know how it turns out...
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Old 12-24-2009, 07:37 PM
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That's an abrasion resistant coating on the top, not clear. Or rather its not clearcoat unless someone's sprayed it at sometime in the past. Its some sort of silica like coating that's way harder than any paint you'll ever find. Its also brittle to the extent that the top sections would have to be formed and then coated. If they tried to heat form a coated flat sheet, the coating would crack.

I don't know whether the corvette top panels are acrylic (common name plexiglas) or polycarbonate (common name lexan), but you'll need to know which before you do anything to them since there's a bunch of difference in the two materials as regards chemical compatability and physical characteristics. My guess would be acrylic, and if I had to do any sort of work to them I'd sure hope they were acrylic. Polycarb is darn near indestructible, and made for applications like bulletproof windows and such that require its toughness, but its one of the most aggravating materials to work with that you'd ever find. Trying to sand it is like trying to sand a week old chunk of used bubble gum. And its highly sensitive to a lot of solvents that don't attack acrylic. I had an 88 with clear top, and a 96 with both tops, but fortunately never had any problems with either of them, so I don't know which material they're made from.

Bottom line though I seriously doubt there's anything you could do to restore them to a condition even remotely resembling new, regardless of which material they're made from, primarily because long term sun exposure damages both materials thru and thru, not just on the surface. Unless you just happen to like the clear panel, I'd be looking for a standard panel to replace it. I've got an 08 coupe now with body color roof panel, and not having the sun beating thru on a hot day, making you feel like you're driving a microwave, is a wonderful thing
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Old 12-24-2009, 09:32 PM
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I believe it is acrylic, But my only bases for that is corvette catalogs that sell refurbished units refer to them as "Acrylic tops"

Ma motorworks sells a replacement for $800 or $1000 without a core. I found out from corvette friends they replace the acrylic with new.

But places like corvette central and eklers will refinish the factory acrylic for $600 So they have to be some way to refinish them. Finding out how may be a much harder process. My car came with both tops from the factory. I have the painted hard top and the glass top. Although I don't believe the hard top has seen much action. I want to keep the glass top. I really like it much better then the hard top. Mainly because it weighs about 1/2 what the hardtop does. And anyone who has owned a c4 will tell you how much of a pain in the *** a hard top is to install and remove.

The top I seen in person that was clear coated looked very good and factory from the outside. I would rather do that then get rid of the acrylic top all together. But I don't like it enough to spend $600-$1000

The jitterbug Idea is not bad. I was thinking of using that or a straight line sander with fine grits. As far as removing the coating and applying clear I don't believe it will be a hard job. But I believe I will have issues with it remaining transparent. And Im unsure how it would hold up. acrylic don't seem to be a good substraght for a clear coat. I wonder if it will peel or turn yellow on me.


I had two more thoughts wile searching the internet for idea's. I remember seeing some stuff in a eastwood catalog made by PPG. It was called "Blackout" It was ment to be used for taillights as a spray on tint. I wonder if it would be a good idea to spray the top with the PPG blackout before adding a clear coat? Im in the process of finding a data sheet for the black out stuff now to see how it works. It may be a dumb idea. But an idea.
Also my acrylic (and all I believe) top is tinted from the factory. Does anyone know if it is tinted on the inside like normal after-market car tint, or is it inside the acrylic as a film, or just a tinted acrylic resin?

I don't know of any strippers that would work on acrylic tops, except for the fat ones they work on anything.......Get it?...Striper's....... serious tho I don't know of any acrylic safe striper's, and if they did make one I would think it would not work well to remove the coating.
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Old 12-24-2009, 09:57 PM
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With the last two post, it don't sound good. If the windex rumor is true then I will have a hard time getting clear coat to stick to it. And same with the post by TubeTek. silica and solvent paints are not good friends.


Polishing my still be on the table. I though about using plastic polishing compounds with a normal 7" polisher The only issue I see would be with the frame the acrylic is set it. It has about a 1/4" metal frame around all sides. Getting a polisher in that gap would be a challenge. same with sanding.
Ive looked a few times to see If I could remove the acrylic from the frame and I don't see a way without special tools or busting it out.

Regardless of the outcome I should give it a try. It may turn out perfect or it may not. Bottom line is it is useless the way it is. I would not want it on my car now, I sure would not want it on after I paint the car. (1991 Steel-blue poly GM25 )


The funny part is Ive got this same question posted on a corvetteforum and it has been two days with no response. Seems like with millions of c4's and c5's on the road at least someone must have at least attempted to repair one. At this point a failure story could be just as helpful as a success story.

Tubetek: The coating you are talking about, would it happen to called "Dulso"
I know on this same year corvette, GM used a coating called "Dulso" to coat the interior trim for a uv protectant. Over the years it cracks and dulls somewhat like the top. The dulso has a almost sticky finish when it is sanded, Before sanding it is hard. If I find out it is dulso coating then I will toss the top. their is nothing I can do with it. That dulso crap is impossible to remove with out damage. I had to remove it from my shifter bezel and I got so tired of sanding, scraping and peeling that I took the gamble and soaked the bezel in lacquer thinner over night. The next morning I found the delso it still be in perfect condition but the bezel to be 40% melted and destroyed.


I thought lexan, acrylic and plexigalss where all the same. Any idea how I could tell what the make up of it is? Other then searching online and taking someone else's opinion?
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Old 12-25-2009, 09:50 AM
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Here is a really good post with pictures of a successful redo of a c5 top.

www.101corvetteprojects.com

then search for refinish

Last edited by cgates; 12-25-2009 at 11:10 AM.
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Old 12-25-2009, 10:43 AM
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Tubetek: The coating you are talking about, would it happen to called "Dulso"
No. Google Lucite SAR That's GE's trade name for acrylic with the coating. SAR is Super Abrasion Resistant.

Looks like the project in the link above came out good. I'd say the odds are very high that the panels are acrylic and not polycarb. Main reason being polycarb is so solvent sensitive that it'd be unlikely for it to survive any sort of automotive paint's solvents.

Assuming its acrylic, you could just polish it once you've removed the coating, but it would scratch easily. When the SAR coated materials came out about 25 years ago, a rep from GE Plastics came to the place where I worked at the time to put on a demo of the new material's scratch resistance as compared to the uncoated stuff. IIRC, they said at the time the SAR coating was about 100X as resistant to scratching as the plastic itself.

Regarding the tint, its in the plastic itself and not an applied coating of any type.
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Old 12-25-2009, 01:34 PM
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WOW amazing job guys! cgates: Thanks for the link, That seems like a handy site. I searched for 30 mins on google looking for someone that had refinished a top and came up short. good job.


TubeTek: Thanks for all the very helpful info. Amazing how much you knew about the acrylic. Thank you!


Last question and we can consider this closed, And I will add an update after I finish the job. The Lucite SAR stuff is it in a sprayable form? Or better question I should ask is can anyone buy it?
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Old 01-28-2010, 05:33 PM
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If you are reclearing

If you want to reclear just sand the clear down with a DA sander. Use either a 400, 500 or 600 grit. Wipe clean and respray.
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Old 08-24-2011, 04:30 PM
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Acrylic vs Polycarbonate

Acrylic is the better for show and can be easily cleaned with many substances. Polycarbonate is 25 times tougher than acrylic but tends to scratch easier.

http://www.iplasticsupply.com/
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