How to feather gloss and matte clear

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PostPosted: Thu Jun 23, 2022 3:32 pm
Hi all,

I have muiltiple spots on the race car where I will have matte clear bordering gloss clear. The hood for sure, but also in the interior. The seam between the clears will be on relatively flat surfaces. I plan to apply gloss first, then matte while masking over the gloss. Can I leave the border between the two clears with a straight masking tape seam, or do I need to feather the two surfaces? I’m worried the sharp edge between the two clears will leave space for one or the other to “lift” or chip at the seam.

Thank you!

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PostPosted: Thu Jun 23, 2022 8:53 pm
A hard edge will be fine, but if you're really fussy then use a fly masked edge on a seam or body line. Don't do it in the middle of a panel.
Chris



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PostPosted: Fri Jun 24, 2022 5:35 am
Thanks Chris. The particular design I had in-mind has the center raised-panel section of the hood in flat black, and the remainder in metallic orange gloss. Plan was to mask the balance of the hood and paint the raised section with black base coat and matte clear. If you don’t see issues with the hard edge lifting on the matte clear, then I will go for it! Thanks!

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PostPosted: Fri Jun 24, 2022 6:34 am
If the area that you want to do in flat clear is delineated clearly as a raised section then painting it first and masking off would be ideal.

Search my posts on "fly masking" where you'll find quite a few mentions of how to do it. Funnily enough, I've just finished watching this video where The Gunman uses the same technique, on a body line for a spot repair. If you get it right you'll end up with a soft edge of a fairly sharp line - so perfect for what you're planning. Because the clear thickness doesn't taper down to nothing like on a clearcoat join there is no risk of it failing due to insufficient thickness.

For a sharper edge just normal masking, but you will have a step you can see and feel.

Thinking about it some more.... this might be better:

Paint your black base in the centre section and allow to flash until tape free. Using a low tack plastic (for a sharp edge) tape mask your edges. Use fly masking that extends just a little over the hard line tape edge, but doesn't touch the part you want orange. Then paint your orange metallic. This will still give you a sharp line but will protect from excessive build on the edge and the dreaded step that then needs 300 coats of clear to bury. Remove masking as soon as the orange has flashed and clear the whole panel with 2 coats normal gloss clear. Yes, I know you want flat in the middle - that comes next but it was important to get the base coats covered within the window so you'll have good adhesion. Denib and sand with P1200 to P1500 all over.

At this point I would just put 2 coats of the flat clear on the raised section(s), extending just a little past the line where I'd want the gloss to end. My gun control may be a bit better than yours so you may want to loosely backmask the parts you don't want flat. Be very careful doing this though - you don't want the masking to touch the surface along the edge so set it back 50mm or so and make sure that it rolls evenly. Now allow the flat clear to cure.

Once dry, sand the gloss area with P1200-P1500 being very careful not to sand over your edge. Use tape to protect if necessary. Carefully flymask along the edge where you want the flat/gloss join and mask the rest of the flat area with paper or plastic being very careful that there are no tape edges lifting where overspray can get through.

Now give the gloss orange area two coats of clear. When you're spraying near the flymasking don't aim the gun so that the paint shoots up under the rolled over edge and builds where the glued backing of the tape touches the panel. Remove the flymasking after an hour or two and allow to fully cure.

Now you can tape along the edge and mask off the flat section (because you don't want compound to get on it and leave marks) then denib the gloss and buff right up to your taped line.

Result should be a sharp line between gloss and flat without any step along the edge.
Chris



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PostPosted: Fri Jun 24, 2022 8:39 pm
Thank you Chris! There is a lot here to unpack so il read and re-read tomorrow. Il let you know if I have any questions. I do have some unrelated questions that will come-up before I get to paint:

1) my hood and hatch are fiberglass. Any special treatment required, or can I just sand with 80grit and epoxy as I would steel?

2) I will be tackling the roof first. From what I read on this forum, this is a good place to start if you can’t manage the whole car at once. I plan to epoxy and apply filler within the re-spray window. have some alluminum filler from Eastwood for the deeper seams that were previously leaded. However, all I have for lightweight polyester is “bondo” brand from my local parts store. Does the quality of the filler matter, or can I go ahead with bondo? Just skim coating, the steel is as straight as I can get it. If bondo is junk, please let me know if you have a recommendation.

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PostPosted: Sat Jun 25, 2022 1:31 am
Ahajmano wrote:hood and hatch are fiberglass. Any special treatment required,



Not really. I like to get fibreglass as straight as I can, with filler if necessary, before I paint. Then epoxy to seal and provide a base for primer. But epoxy first, then filler, is just as acceptable.

Ahajmano wrote: I will be tackling the roof first. From what I read on this forum, this is a good place to start if you can’t manage the whole car at once. I plan to epoxy and apply filler within the re-spray window


Good plan but you don't need to apply filler within the "window". Anytime afterwards is fine if you scuff/sand the surface first.

Ahajmano wrote:have some alluminum filler from Eastwood for the deeper seams that were previously leaded.


How are you going to get aluminium to stick to lead or steel? If there's lead in there now and it's still ok then I'd leave it. If the body is aluminium then you can use aluminium brazing to fill voids but this won't work on steel panels. So if it's steel then you can use a tin based filler in a similar fashion to the way lead was done, but with reduced health risks. Alternately, any quality polyester filler should do.

Ahajmano wrote:all I have for lightweight polyester is “bondo” brand from my local parts store. Does the quality of the filler matter, or can I go ahead with bondo?


Bondo was available here years ago and was absolute garbage in those days. Regardless of what they've done in terms of improving the product (and I understand that it's now quite good) the name here is so bad that they'll never get even a foothold in the market. There is one Australian made filler that used to be pretty ordinary but the company was taken over by PPG and the filler is now quite good, but most shops use either 3M or one of the bigger European brands. They're a lot finer and easier to sand than most of the American brands that I've tried which were like putting beach sand on your panel. One of the Evercoat fillers I tried was like that but another was completely different. I only use 3M these days. Only a little bit dearer but way better.

Some of the guys more local to you can make better recommendations on what is available there but remember that much is personal preference.
Chris



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PostPosted: Sat Jun 25, 2022 10:58 am
Thanks Chris! I just bought a pail if the 3M platinum plus filler on Amazon. Doing a full car restoration, I don’t want to mess with poor base products. The inefficiency catches up to you.

On the alluminum filler, it is still polyester filler. It just uses alluminum in place of short-strand glass fibers if I understand it correctly. It’s designed to be stronger than regular talc filled polyester (resist cracking), but more flexible than fiberglass filler. It seems to have good reviews and the application seems to match the description in my auto body textbook (I’m a nerd).

I removed the factory leaded seams for a few reasons. One, it’s a race car and I removed a total of 17oz. Kinda shocking there was that much. Two, I was sick of the lead vaporizing (health hazard) and melting near my welds when I was stitch-welding the OEM lap joints (another race car thing). Lastly, the paint had lifted at every spot that was leaded. That tells me the unibody flexing at those locations was too much for the finish to stretch, and those body panel joints needed to be welded (requiring the lead to be removed). The car was already converted to the race car in the 90’s, but had been sitting (and rusting) for 20 years.

Thanks for the tip on the body filler within the Epoxy window. I had read that in the “tips” sticky post, but I understand why it wouldn’t be necessary if the surface is scuffed. I DA sanded the original base/clear off and block-sanded most of the filler until bare metal patches started poking through. Still have some low-spot patches with base still showing. It’s time for sealer since it looks like leopard print and I need a uniform surface to start from. The 3M guide coat has a hard time showing through with Such extreme colors all over the place.



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PostPosted: Sun Jun 26, 2022 10:23 am
Sprayed DTM primer into the engine bay and front wheel wells last night. Going to try the fly masking truck youprovided Chris, this time between the silver base/clear in the engine bay and the transition to the 3M asphalt undercoating in the wheel wells. Going to have the undercoating be the “overlap” onto the clear, near the fender mounting flange but hidden under the fender.



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PostPosted: Tue Jun 28, 2022 9:21 pm
Just made my first post asking a question about paint work and was reading some of the other posts. I'd love to see a pic of this car though! What kind of 90s race car are you working on? Do you plan on racing it again or are you restoring it? Sounds pretty cool either way and again if you have any pics would love to see what this thing is! Good luck with it!



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PostPosted: Thu Jun 30, 2022 10:51 am
Hey there :) It is a 71' Datsun 240z race car. I posted pictures on this forum under "Completed & In Progress Member Projects".

You can see many more pictures and videos on instagram @240z_restomod

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