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Sanding ?

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in process of body repair and sanding, on the places (paint) that are not going to be taken down to bare metal do you just need to break the glaze or shinny coat of paint, using 120m and 220 grit. and what do I need for final grit before paint (400). plan on using a sealer, then base color then clear coat.

This is 411 sunburst yellow, am using light grey primer on the repair areas, do I have to use the same on ALL of the body to achieve a uniform color at the end or can I just leave the unrepaired areas yellow and just primer the repaired areas?

Also the hatch and fenders are a dark brown I assume I need to gray primer those entire items for uniform colr to match the rest of the body.

Car has been painted before and looks like it is still adheareing very well except around the body rubber/gaskets which are now removed and those areas will be taken down to bare metal and featherd in smooth.

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Donald,

I've painted two cars in my life, both in my garage and both turned out pretty nice. Here's my feedback.

If you feel the existing paint is sticking well to the body, that paint can be wet sanded with the proper grit and then primered/painted over top of.

I don't think your primers need to be the same color provided you spray a uniform/thickness of paint. However, different colors of primer may trick your eyes into thinking you have thin areas and you'll paint more in those areas. I recommend that since you've gone through all the work and expense of prepping your car for paint that you primer the whole car with the same primer and primer color.

I'd be more concerned that ALL of your painting supplies would work together as a team. I believe that the sealer, primer, base and clear coats should all be from the same manufacturer. I've been told not to mix materials from different manufacturers.

Sanding grits should be called out on the Tech Sheet from the appropriate manufacturer. Use those to determine how to prep the surface as well as your mixing ratios and cure times. I got a lot of advice from the paint supply house where I bought my materials

Others here are much more experienced with painting cars, hopefully they'll post their thoughts. Good luck with your efforts, lets see some pictures of your car when finished.

Bruce

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Don;

There's been several threads started and discussed at length on this. Not trying to give you the "Do a search" routine answer, but there is a LOT of material that has been discussed.

If what you want a short, nitty gritty, "Earl Scheib" type of answer, i.e. the Cliff's notes version:

Taking the paint "down to the metal" is only necessary if the existing paint AND primer is bad OR if you have the time and money to do a paint job like they show you on "American Hot Rod".

Don't wet-sand to or around bare metal if you don't absolutely have to. You're asking for more problems on a number of levels.

Use a D/A sander with 220 over the complete car to SMOOTH the existing paint and reduce it's thickness. In the process you'll be leaving 220 size scratch marks which are sufficiently coarse enough to apply your fill primer on top of.

Filler primer is used to build up the panel to further SMOOTH the body panel via sanding. Fill primer is generally applied OVER etching primer.

ETCHING primer should be used wherever you have bare metal. A metal etching solution as a prior step to the etching primer is usually not necessary, but not necessarily a bad idea. However, note that SOME etching primers will NOT work well on top of previously etched metal. The key is to know that it will work with the materials you are using afterwards.

PPG sells a wonderful metal etcher, which will work very well with their epoxy primer, or their fill primer, or the various brands of polyester body filler. However, it will cause major problems with lead-free solder's tinning solution (required to make the solder adhere well), or with another brand of epoxy primer. So the bottom line there is to know what you're working with and what you will be putting on top to make sure everything will work together.

There are has been a ton of discussion regarding whether you should do body-work on bare metal, or on etch primered metal. I'm referring to plastic body filler. Both sides of the discussion make good points...YOU decide what you want to do.

Let worked plastic body filler cure for as long as possible before you primer / seal over it. This means you apply it, you shape it, and you smooth it, then you let it sit either under infra-red lamps to help de-gas it or you wait several hours / days (again, many different schools of thought). This is to ensure that you don't trap any solvents that should have evaporated AND to ensure that shrinkage AFTER you've applied paint is minimal and hopefully unnoticeable. Your final smoothing on bodywork will range between 220 to 280 or 320 sanding paper, which still leaves some "tooth" for the fill primer to bond to.

Most bodymen will advise doing a full fill primer coat or two on top of any body work to make sure you have a fully smooth surface without having to rely much on glazing putty. (Red Cap or "Icing" body filler) Your final sanding on the fill primer will be with 400 grit. Again, this still leaves enough tooth for the SEALER to adhere to.

Definitely allow glazing putty to cure before you sand it, and let it cure AGAIN afterwards. (See the shrinking problems above.)

Use a SEALER on top of all this. This is the final coat over the WHOLE car to ensure compatibility between the base coat of paint and the surfacing compounds already on the car. This also provides a uniform color base to enhance the paint from the first coat out. Generally, most sealers are NON-SANDING..as long as you stay within the time guidelines provided by the manufacturer. Wait too long and you WILL have to sand, don't wait long enough and you'll have problems. READ the sealer material's tech sheet.

As pointed out by Bruce, you won't be over-painting to achieve the same color. The money you save by not sealing the whole car is very poor economy when you consider you could run / sag / orange-peel / craze / blush / crack a paint job by uneven paint spray. Again, READ the paint material's tech sheet.

2¢

E

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I would say absolutely have the same colour undercoat all over especially with a yellow top colour. One of the yellow submarines I work on had a respray with only the damaged paint getting a hit with primer. End result was a sub that looked like a spotted cow.ROFL

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Thanks for all the info, think I got what I needed.

Jmark, not this one, think I,m gonna try this one myself, dont wanna get alot of labor dollars tied up in it and hell I cant do worse than the first JA that painted the blue one (not shane).

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I wanted to make sure that I was reading this thread correctly. The whole car will be yellow? If so, don't do what so many before you have done and ended up regretting. Ever seen a yellow paint job that had what I call "Green Spots"? Thats what you get with yellow over either the unprimed areas, or the primed areas, depending upon the sealer coat or lack of a sealer coat. Confused? You should be...Do what I do, and I guarantee you will love the results.Yellow is a pisser of a color to spray evenly without the help of a white ground color.That's right...spray a coat or two of white base, just like you would if you were painting the car white, let that dry a good bit, enough to be able to run a basecoat tac rag over it, then follow up with your yellow and watch how much easier it will be for you to achieve the best yellow finish in town! Good Luck and happy spraying!!!

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Excellent point!

Too often inexperienced painters forget that the BASE paint's color is Primer/Sealer color.....then followed by the COLOR paint of your favorite hue and effect; and then the CLEAR paint.

The Base paint's color will definitely affect how THICK the next coat has to be before it evens out in color.

As John pointed out, yellow paint is very much translucent to a degree and it will pick up the differences in the base it is applied onto. Paint red oxide primer and see how many coats of paint you have to apply before it LOOKS yellow.

So use White Sealer over your primer and you'll not need to get more paint, just make sure the sealer you use is white.

Good point John!

E

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ok lets see if I understand this right, do my sanding and bodywork, prime where needed, then sand to 400 grit, seal with a white color sealer, tack rag it, spray my yellow base coat, tak rag it, then spray clear and do the wet sanding then buff/polish!!!!

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Just a second. The type of sealer you use may not be wipeable with a tac rag. Some tinted sealers will dry quick and can be wiped accordingly, while others will remain a wee bit tacky and should not be touched. Find out from your paint jobber what youv'e got and wether tacing it off is adviseable. Everything else you said sounds like your ready to give it hell,,,Go For It...John

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...snip...Some tinted sealers will dry quick and can be wiped accordingly, while others will remain a wee bit tacky and should not be touched. Find out from your paint jobber what youv'e got and whether tacking it off is adviseable....snip...
...snip...I'd be more concerned that ALL of your painting supplies would work together as a team. I believe that the sealer, primer, base and clear coats should all be from the same manufacturer. I've been told not to mix materials from different manufacturers.

The bold highlights the important points here.

John's point is dead on...Want to find out the hard way? Go ahead and tack and see if you don't end up with fish-eye's , crazing, the lint that the tack rag had picked up before sticking to your fresh sealer...Get the picture?

But Bruce's point earlier is also right on the money, Spot On as our Aussie friends would say. "Find out from the paint jobber" is more than "Should I use sealer?", it's more along the lines of "Do you have the technical sheets on these products?". While it may seem pedantic, or even "snobbish", what you're trying to find out is process times, methods, and most importantly....compatibility.

The majority of products you are working with have certain windows of time within which you can do certain processes, and outside of those windows (and depending whether before or after the window elapses) whether you can do the process at all.

As an explanation, most primer/sealers I've worked with recently are of the NON-Sanding variety. That is, you don't NEED to sand it before you apply the next coat of paint. However, there is a distinct time window of opportunity. You can't do it before the window opens, and if you wait till the window closes, now you MUST sand in order to get the next coat of paint to adhere properly. There are certain Do's and Don't Do's within that time period. No sanding can also mean no tack-rag, or don't cover or lay anything on the surface or even handle at all. While some sealers are very forgiving, others are very touchy....to find out what you have, you read the tech sheet.

Good points John and Bruce!

E

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Hey guys, there is a material used at a seam I need to know what to use it is where the roof line meets the rain gutter, appears to be some kind of caulk that got hard semi hard and cracked up!

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It may be what is called seam sealer. You should be able to get it at any auto body supplier. I use Evercoat brushable seam sealer,1qt. is $14.37 from Eastwood.

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Also note the thickness of your application of seam sealer in this area. Too heavy and you may have a time getting the drip rail back on. Keep it thin and even and all should go well. And let it dry as long as possible before applying primers or paint.

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Pretty close to painting, 2 questions! not sure if I will have the fenders soon enough so thought Id paint everything else now, Q #1 how much base color should I buy and will the colors match (fenders) if the base is out od the same batch or does the reducer effect the color?

Q#2 is it ok to wash the car prior to painting to remove all the fine dust and crap?

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My 2¢

I would definitely wait until you have all the body parts to be painted to paint ALL of the exterior in one shoot. You can get away with shooting door jambs, hatch and engine bays, but once you start "patching" fenders, doors, etc. you are asking for ever so subtle differences in the finish.

While the reducer itself is not necessarily the main reason for paint variation, it CAN be. The humidity, temperature, even the barometric pressure can affect how the paint flows from one day to another.

Toss in that you would more than likely be painting the fenders on sawhorses and now you have position that can affect the look of the finish. While this is minimized with basic color paints (i.e no Pearl, Metallic, or other appearance modifiers) it is nonetheless something that should definitely be considered.

Metallics and Pearls are the most sensitive to this phenomenon.

As far as how much paint, that depends on your skill in painting and how many "coats" you'll be painting. Typically, you're talking a "mist" coat, followed by two or more "double-wet" coats for your basic color. Some people will add a last one with extra reducer to reduce the amount of "orange peel" effect. Again, it depends on your skill.

Clear, if painted on the same day may in fact reduce the amount of color you can or should paint. Clear is even MORE sensitive to excessive paint and it is extremely easy to RUN/SAG it. This is even more exacerbated by the fact that you cannot readily "see" it.

If you are talking a COMPLETE color change (i.e. door jambs, hatch, engine, interior) then at LEAST a gallon. It might also behoove you to buy the gallon as it might be cheaper than buying 3 quarts and then you don't have to batch mix all three quarts together to ensure color consistency.

Washing the car is ok....as long as you thoroughly and completely dry it. Use copious amounts of water as opposed to soap.

Use a wet cotton rag to wipe down all surfaces to remove any powder or dust that may still cling. Once you're finished washing, use the wet rag to wipe off any water, squeeze it dry whenever it gets wet and do it again. Use it just like if it were a chamois. Then go back over the whole car with an air blower and blow into all those little nooks and crannies that can trap water. If you find trapped water, use the blower and blow it out onto your rag. Use the rag to trap those runaway drops, don't let them evaporate on the car via the air stream.

Your last step before beginning to paint, is a final application and removal of Wax and Grease Remover. This will ensure that there are no human or other oils on the surface of the car. This is wiped on, and wiped off dry...again, don't let it evaporate.

A tack rag shouldn't be needed, as you will have cleaned the dust off the car, but you will definitely want to squeegee the floor of the booth, or at least wet it down (not puddles) to keep any dust and dirt off.

HTH

E

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NO!!!

Lacquer thinner will CUT and LIFT your primer, sealer, and red cap if you used it.

Check at the store where you will be buying (or did buy) your paint. Ask for it by name, and all you need is the small quart can. Some people have used Mineral Spirits and while some have said no problem, others have reported crazing and fish-eye. For the few bucks, it's cheap insurance.

Remember, you've done too much GOOD work for you to risk it over a few dollars. Remember, 80% of body-work (if not more) is intended to be INVISIBLE after the paint is applied.

One thing about a tack rag I didn't mention earlier, it is usually a resin impregnated cheesecloth. This resin is used to both capture and remove any dust / dirt / lint bits that may creep onto the car, and also to neutralize static charges you may have imparted in wiping down with W&G, and other actions. (Some people recommend using a ground strap attached to the car and to earth ground to eliminate static charges.) All of these are items you need to evaluate for yourself, but do be careful not to smear the resin onto the car's surface. A LIGHT touch is all that's needed with a tack rag.

E

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Thanks E, do you see a prob with putting down a sheet of plastic under the car to protect the floor during painting?

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While I think that if you wash the floor and it's still damp (not wet and puddly) you won't have paint mist to worry about unless you actually spill some paint.

Just make sure the plastic sheeting is held down well and can't be fluttered onto your paint via your paint gun air stream or even casual kicking of it. If you do use the plastic, be very careful about any water that may drip onto it...it can be kicked up and onto the car very easily.

I think Mat M, or the IanMonster had a problem with plastic sheeting blowing onto fresh paint.

E

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Thanks E, went ahead today and tried my first paint, had a pint of single stage and painted the underside of the hood and the underside of the hatch, not to bad for a ROOKIE!!!!!

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post-7742-14150799718462_thumb.jpg

post-7742-14150799719334_thumb.jpg

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:smoke: If this is your first attempt, and it's Single Stage at that...Youv'e done very well young Jedi. When you step up to BC/CC you should get even better results, as in my opinion, single stage paint may be easy enough to do, but a good BC paint is heaven. Keep it up and post those pics as you progress, and as E said earlier, paint only when you have everything you need and can do the complete job at one time. Trying to colormatch anything with so little experience would not be adviseable. I paint everyday and can say that it's the least favorite part of the job.

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I agree.

No sign of dry-line, mottling consistent with a single stage paint but not too excessive. Color appears consistent and even...I'd give it a passing grade for sure.

Now when you go painting the exterior surfaces, scuff up to the edge, but don't get fanatical about it. Then when you mask, mask just INSIDE that edge so that there is a space for it to blend in smoothly without leaving a paint ridge.

E

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