Sand door jambs

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PostPosted: Sat May 23, 2020 5:40 am
Dokus wrote:Weird, I didn't see the other post when I replied last. I fixed the peel and rust in normal fashion, sanded the jambs like the rest of the car up to p320 blocksand. Next up I plan to do 1-2 coats epoxy and 3 costs of primer. Continue sand 400 to 800 before standohyd base. I use mipa acrylic primer 4+1.

I have no plans on using sealer, just reprime areas if I burn through. I just paint on my spare time so I'm not sure but sealers does not seem to be commonly used in Sweden. Non of my suppliers sells sealers, only some primers that can be thinned to use as sealer.


Epoxy primer is a type of sealer. There are two types of primer, sandable and non-sandable (with sone variations like epoxy or self etching.) Primer you do not sand is generally considered sealer. Epoxy has properties to help seal out air and moisture. Its basically sealer that is especially suited for bare metal.

If you sand the jambs with 320 I would suggest hitting them again with 400 then 600 and shooting one coat of epoxy primer and shooting your base over that. Im still not sure why you want to shoot a bunch of filler and blocksand? We are still talking jams or no?

Personally I learned the hard way not to spray base directly over sanded filler primer at least not with metallics. Sonehow sand scratches always show even after 800 grit. I will admit I probably never sand enough tho.



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PostPosted: Sat May 23, 2020 7:07 am
NFT5 wrote:P400? Why, unless you're taking out imperfections? Even P600 is too coarse under a metallic and scratches will show.


First of all everybody has their own methods for painting cars and to each their own. If you had read what I wrote I mentioned applying sealer before base. You can shoot sealer over 320 grit and base right over that with no issues.

Wash first and then Prepsol, before you start sanding - otherwise you'll be sanding the contaminants deeper into the surface. Don't forget to blow with each tacking process. Most of the newer sealers specify wet on wet application with no tacking or denibbing until after the first coat of base. OP should use the procedure outlined in the TDS for the product he's using.


I tried to outline all the steps I guess I forgot to mention you have to clean the area before sanding. Its common knowledge if OP knows enough to even know what epoxy primer is I have to assume he knows to clean the area before sanding it.

Not true. Scotchbrite was developed specifically to provide a suitably keyed surface for subsequent coats of paint. It's recommended by paint manufacturers as an acceptable substrate treatment.


With what a brand new red scuff pad? Good luck painting directly over that surface. If you scuff with silver or gold youll at least need scuff gel or youll be at it all day. Its much faster to sand the existing finish like I said and after sanding scuff with a grey pad before sealer.

As for film build, if the paint in the jambs is original factory then it's likely to be in the order of 100μm. Adding sealer (20μm), base (20μm) and clear (50-60μm) will take DFT to around 200μm which is well below the 300μm threshold that should not be recoated.


I dont know where you got these numbers from but I will just assume theyre accurate. Regardless, if you simply paint over the existing paint you will not end up with a factory finish or anything close to it. When I was just learning painting friends cars in my garage I did what you are advocating and the end result never looked right. That could be for reasons unrelated to overall film build and I guess I should point out that whatever I say is always just my opinion from personal experience.


Garbage. Mixing base with clear, apart from potentially putting together incompatible solvents or water with solvent is just going to reduce the coverage. If you need 2 coats to get coverage then 1 coat of a reduced strength product is never going to work.


I was taught to do this and have done it many times with zero issues. You go right ahead and shoot door jambs and the underside of hoods and trunks like you do the rest of the vehicle. If thats what you prefer, probably because you get paid by the hour and are not paying for materials, more power to you. My method saves time and material. I have to assume op knows not to mix water based paint with solvent based clear.


Rubbish. Use the correct shade of sealer or primer as recommended for the formula of the paint you're using. The paint colour is designed to go over a particular shade and if you vary from this then you'll either struggle to get coverage or the colour won't be true and therefore not match


Did you even read what I wrote? I said nothing about value shades or anything like that. The author of this thread is not a full time professional painter. That much is obvious. Your advice is correct but your intended audience is definitely not going to search out what value shade primer to use. Hes most likely going to buy primer from a local supplier and has little idea what color to use. I was trying to help him avoid having issues with his color.


You do NOT want coverage in a single coat. This would require an overwet application with potential problems such as solvent pop or runs.


You want to bet on that?

Well at least I can agree with most of this. Note my earlier comments about P400 or even P600 being too coarse as a prep for basecoat.


I dont recall advising he base over 400 or 600 grit sand scratches. I advised applying sealer before base.


One coat means one coat, not 1.5 coats. Sealer is not a filler and should never be relied upon to rectify sanding scratches. Apply sealer as detailed in the TDS for that product.


Shoot sealer however you like. I shoot it how I was taught and im perfectly happy with the results. For what its worth I bet we both would use about the same amount to achieve one coat with yours being applied a little wetter than mine. Ive gotten runs in the past shooting sealer too wet so my style feels more reliable to me. I probably posess 60% of your skill and OP less than that. I shoot how i feel most comfortable and confident.

Here is the bumper painted and put back together. I shot it in the street with a 5 gallon air compressor. I do lots of things people like you would strongly advise against. Im pretty happy with the results i get with my methods. That is off the gun and up close its for sure not perfect but i am not going for perfection i am prepping the rv to sell. I tried to blur out the license plate and thats why that area looks funky. The owner is more than pleased. Just pointing out the fact that you can get good results many different ways.
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PostPosted: Sat May 23, 2020 9:13 am
Methyl Mike wrote:everybody has their own methods for painting cars and to each their own.


nice_blend.jpg
nice_blend.jpg (20.87 KiB) Viewed 73 times


I rest my case.
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PostPosted: Sat May 23, 2020 12:02 pm
M/M I think your stretching it a little. I've used sealer that specifically said to use over 320, it didn't work. even back when we all used A/E your paint job would look great for about a week or two then things started to shrink up, and the 320 sand scratches would start to appear. same for the B/C application. metallics are just going to magnify this. your best bet if you or anyone wants to use 320 as there base profile is to use epoxy as a sealer. it might have less shrinkage but 320 is not really the proper way to start a paint job.
Jay D.
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PostPosted: Sat May 23, 2020 12:17 pm
M/M what kind of base and clear are you mixing together? I did a little more reading and your statement to mix base with clear is not good information. back when we used A/E or S/S products it would work, and was a common thing to do. you could really brighten up a metallic job by doing this. I've tried this with base and clear it just doesn't work, that's with all the base products I've used. they are two different products.
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PostPosted: Sun May 24, 2020 5:58 pm
NTF5, once my epoxy and high build is painted. Which grits do you suggest I should use to sand the primer before base? I will end with p800 before base but I was planning to block p400, 500, 600 dry before 800. Unnecessary work? Should I do just 800 wet? Bodywork should be done so it should hopefully just be to get the primer flat.



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PostPosted: Sun May 24, 2020 7:48 pm
NFT5 wrote:
Methyl Mike wrote:everybody has their own methods for painting cars and to each their own.


nice_blend.jpg


I rest my case.


I dont recall this thread being about blending. How weird.



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PostPosted: Sun May 24, 2020 7:53 pm
badsix wrote:M/M what kind of base and clear are you mixing together? I did a little more reading and your statement to mix base with clear is not good information. back when we used A/E or S/S products it would work, and was a common thing to do. you could really brighten up a metallic job by doing this. I've tried this with base and clear it just doesn't work, that's with all the base products I've used. they are two different products.
Jay D.


I have done it many times and a quick google produced this http://www.spiuserforum.com/index.php?t ... lear.4603/

I got the idea years ago from another painter at a shopni rented a booth at. It works fine. In fact when my friend gets back ill take a couple pics of his truck it was the first job i ever did and still looks great. I painted the jambs under the hood and the inside of the bed all like that.



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PostPosted: Sun May 24, 2020 8:04 pm
A better explanation: i cant get the video to embed properly here is the youtube link https://youtu.be/9RymvsfpeWo
Last edited by Methyl Mike on Sun May 24, 2020 8:12 pm, edited 1 time in total.

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PostPosted: Sun May 24, 2020 8:11 pm
Dokus wrote:NTF5, once my epoxy and high build is painted. Which grits do you suggest I should use to sand the primer before base? I will end with p800 before base but I was planning to block p400, 500, 600 dry before 800. Unnecessary work? Should I do just 800 wet? Bodywork should be done so it should hopefully just be to get the primer flat.


Watch my reply in this thread where I cover all of this.
Chris
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