Okay so I want to paint my engine bay within the next couple of weeks, but I have some questions.

I have painted rims in the past with spray cans, and they turned out pretty good, but this time I am using a air powered spray gun. The way I did my rims before was a sanded of all the old clear coat, scuffed the rims. Some coats of primer, coats of base coat, and then coats of clear coats. I am assuming a car is the same procedure, but from reading guides everyone has done it differently.

My main concern is that the engine bay was originally white, and one of the previous owners had painted it black. I am unsure if it was done properly or not. I have seen people just scruff it all up and then base coat it. This to me seems like it won't last forever. I want to do a good job with this, and not want the paint to start chipping to soon.

With that being said should I be sanding down to the bare metal than priming it after? Do to it already being painted twice(As I know of).

 

sand down, seal, primer, block sand, seal, basecoat, clear would be the correct way to do this

 

you dont need to go all the way to metal unless the paint chips off when you sand it. just sand it to break the top coat or feather out. id use some 180 grit paper to do that. Then prime it with 2-3 coats of a urethane primer. sand that with 400-600 sand paper. then paint it. and clear it.

 

When you talk about sealer what exactly is that. I was under the impression a sealer was the same as a primer. Because at the paint automotive paint shop I told the guy what I had planned, and he misinformed me. I asked for some sealer, and he said a sealer is a primer. He told me all I would need is a base coat and some reducer to do the job. I felt as I left that place with not enough supplies to do the job right.

What if there are some chips in the paint, and I can see the factory paint? Should I just sand until smooth and go from there?

 

Thats why I said you would have to seal out other layers of paint. Epoxy primer is for sealing out things from the layers below and also works as a corrosion protector for bare metal. What kind of paints did you get?

 

I've used POR-15 in the past. It works well.

 

ok ... no and secondly NO

here is the problem if someone paints synthetic enamel from a spray paint can in the engine compartment to change the color and you go right in with some urethane or acrylic enamel professional paint it will start wrinkling up like the texture on your valve cover.

What you want to do is test the paint for type and then decide if you need to put primer on it before you base coat it.

The way you test for synthetic enamel is by taking a few paper towels and moistening them with paint reducer.. don't use a lot just enough to get them moist.

If you scrub the paint with the towels and it comes off then you need to use primer.

since engine compartments are difficult to work in with all the tight places and complex areas .. meaning its not a flat hood then it is probably best to use primer sealer on the surface to give you a fresh barrier between the synthetic garbage paint and the good paint you will be putting on it.

As long as the paint is in good condition you can scuff it with a gray scotch brite pad you can get at the paint store.

Then put primer sealer on it that does not need to be sanded.

Let the primer cure and then you can paint your basecoat or single stage paint over it.

Primer surfacer will require sanding before you paint it that is why i suggest primer sealer which does not require sanding unless you let it sit for over 8 hrs.

I do not suggest an epoxy primer that stuff pretty much sucks for any area you want to look good .. its just too much to deal with. If you had a ton of rust maybe but i don't even like it then for any area that is going to show.


So .. test it.. if it comes off real easy then primer seal it.. give it the recommended flash time and then start painting.. if you get a run you can cure and sand it lightly .. if you take more then about 8hrs before you start painting color let it cure overnight and scuff the surface before you start applying color.

 

Okay, the type of paint I am using is made by 4th dimensions. I believe it is an acrylic paint because it says it contains acrylic Polymer along with a bunch of other stuff. I did not see Urethane anywhere.

Am I able to buy sealer, and primer for the spray gun? Or can I use spray cans for the sealer and primer, and the rest with the gun?

What do I use for a reducer? Paint thinner? What ratio do I use to mix it with? Do I need to mix a reducer in with the primer, base coat, and clear coat?

http://www.carcraft.com/projectbuild...g/viewall.html This is the guide I was looking at, but they are using a different paint which requires an activator to cure properly I think.

 

The ratio should be on the cans, if not you can ask the supplier for the p sheets.

Sealer is a product ment to protect from corrosion on bare metal and when reduced 10% will lay down flat unless you suck at spraying. Crx it seams like you have somewhat of an idea but off on epoxy and prob following what somewhat else has said. If sprayed correctly you will not notice any epoxy (as a sealer), and should be about less then a mill thick.

 

There are a variety of different types of primer

There is Primer Surfacer that most people know.. its used to sand out small scratches you apply a few coats and wetsand it.

There is Etching Primer that is used to etch into bare metal and give it added rust protection .. no one uses this that much though.


There is crap like por that is said to be an epoxy that helps convert or seal out rust.. yeah sure it does.. well it is good for under your carpets and in your wheel wells but I wouldn't put it on any surface thats going to show.

Then there is primer sealer.. it is used to provide you a fresh surface for painting.
Primer Sealer can be used over Lacquer, enamel, urethane, body filler, fiberglass. Its sole reason is to seal out what is under it so whatever is under it wont effect the top coat.

I personally like the Urethane Primer now .. the 5star urethane primer surfacer can also be thinned down real thin and used as a primer sealer not to be sanded. and Urethane is hard as a rock

Yes you can get primer in any type to work in a HVLP Spray Gun .. I am assuming you are saying you are using a professional type spray gun attached to a air compressor.

The products that you use for mixing your paint should be supplied by the paint manufacturer.

You use reducer and maybe a hardener for acrylics .. you use activator for and maybe reducer for urethane paints.

Mixing ratios are also paint specific. Some paints come ready to paint out of the can with no reduction.. the garbage paint you can get at AutoZone is lacquer paint and its ready to shoot...

All other products must be mixed at the time you are using them..

You only mix one cup at a time .. / some cups are 16 ounces so you use a mixing cup that you can get at a automotive paint store they have the ratios on the side of the mixing cup

Ask them how to use it.. but there are 3 marks usually .. you find your ratio 4:1:1 then you fill to the line on the 4 and then add 1 of activator 1 of reducer for urethane paint

good luck

you can probably just paint that thing if you use wax and grease remover on a rag after you sand and scrub it down...

Primer Sealer can be bought in a spray can .. yes it works ok but not like the type you mix up... same with all primers and paints.. you can get them in a can but the professional version that you mix and shoot from a gun is 1000 times better

Good Luck

 

So I went to the paint store and bought a bunch of paint supplies to start working on my engine bay.



The guy at the paint store said I did not need the primer you mix. When I did ask for that primer. Instead he sold me some professional rattle can version. It says this is a high build/filler primer.

I also started to sand down the sides of the bay. How is it looking? I think I might of way over sanded in some areas.

 

Please be specific as this can easily confuse the OP, Self etching primer is used only on bare metal.. You don't want to use the wrong primer as it will defeat the purpose..


You cannot Use por-15 as primer.. think you meant for rust but that is off topic..

Now This is well put! Although I'm sure we all know if you want the HIGHEST level of quality, its best to bring it down to the bare metal seeing as theres already 2 layers of paint. (not knowing how it was prepped or if there's also primer underneath.) But with all the tight area's as stated above, it would take ages!


Also if this is your first time shooting with a airpowered spray gun, I highly suggest you do a few test panels with tight spaces.. its easy to try and reach a tight spot in one instance but make a run in another.







In these pics, all those bare metal spots need to be covered in atleast a coat of self etching primer to get the best adhesion. I read above that someone said you can use a grey scuff then primer.... THIS IS NOT TRUE! Grey scuff is almost equivalent to a 600ish-800grit. We use grey scuffs before paint!

Use sanding blocks when sanding the bay also, they have flexible and hard. Your fingers will leave grooves and un even areas.

 

Also FYI that high build primer IS pro-grade but still doesn't have the best quality.. you cant adjust air pressure or nothing so its less accurate.. like it reads, it builds high and fast. Dry to touch in like 20 mins but when I use this on minor metal areas, I prefer let it dry overnight and wetsand the following day.

 

So technically speaking do I not have to remove all the old black paint off. Because this is no way I will be able to get it all off. I have been sanding with 320-400 grit sand paper.

I started working on sanding the firewall but it is much more of pain to try and get all the old paint off. I might just try to sand it up as much as I can than prime it.

So could I basically just go over all the bare metal spots with primer.
Wet Sand
Prime again
Scruff it up
Base coat
Than start clear coating.

 

Thank you this help me as well!! Post pictures when your done