Author Topic: Is stripping absolutely necessary as a prep to painting?  (Read 1393 times)

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Offline clark gable

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Is stripping absolutely necessary as a prep to painting?
« on: March 15, 2012, 08:33:21 PM »
my understanding of painting prep is the following:

1) Strip and sand;
2) Degrease;
3) Clean with a quick flashing solvent;
4) Etching primer, not heavy;
5) High-temp engine paint, not heavy;
6) Cure paint as per instructions;


But is stripping absolutely necessary? I'm really dredding this. Can't i just degrease and clean it really good and paint over the existing coat?

Offline grcamna2

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #1 on: March 15, 2012, 08:50:44 PM »
I've done that..if you go back & forth between the soap and water and possibly acetone a couple times and rough up the shiny areas between all that you'll be fine. When you really "rough it up" in any areas that are suspect of loose,flaking paint or oil underneath that paint..in other words a ton of prep goes a long way.It's possible that sand or glass bead blasting could be faster...until you add in all the clean up from sand in the many crevices...;it's you're call. Prep...a Very time consuming process but very well worth it !
« Last Edit: March 15, 2012, 08:58:14 PM by grcamna2 »
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Offline seanbarney41

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #2 on: March 15, 2012, 08:53:12 PM »
also if you don't strip, skip the etching primer...it don't do nothing unless it contacts bare metal.
If it works good, it looks good...

Offline LesterPiglet

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #3 on: March 15, 2012, 09:31:17 PM »
On the other hand the new paint may react with the old. Been there done that.
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline clark gable

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #4 on: March 16, 2012, 08:46:39 PM »
my first concern is that too thick a layer of paint may inhibit the engines ability to cool down adequately, and accelerate its demise. thoughts?

Offline LesterPiglet

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #5 on: March 16, 2012, 08:48:58 PM »
Never heard of it. Just don't use a 4" brush to apply. :)
'Then' and 'than' are completely different words and have completely different meanings. Same with 'of' and 'have'. Set and sit. There, their and they're. Draw and drawer. Could care less/couldn't care less. Bought/brought FFS.


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Offline clark gable

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #6 on: March 16, 2012, 08:56:38 PM »
awesome, thanks fellow.

Offline Terry in Australia

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #7 on: March 17, 2012, 03:19:36 AM »
Your description is "text book" mate, but in truth, you can do it a lot easier. First off, degreaser is your friend, so buy lots of cans of solvent (not acid) based degreaser, (or Turpentine, it's great, but more expensive) and a range of cheap paint brushes so you can all the goop out of all the nooks and crannies.

Once you've degreased it, get a 3M nylon scouring pad (I steal mine from the kitchen cupboard under the sink, I don't know how they get there, but there's always a plentiful supply there, just use a new one, not a greasy one) and rub it over everything you want to paint to provide a "key" for the new paint, and to remove any oxidation. if you need to remove a section of old paint, use some "wet and dry" sandpaper with water, but if the old finish is OK, just use the scouring pads. 

Use some Prepwash (not thinners, acetone etc, they're too aggressive, and might "lift" or bubble the old paint underneath) to remove any greasy fingerprints, wipe it dry, then hit it with a light coat of etch primer (etch primer is needed to bond paint to aluminum, so it's important that any bare metal areas are lightly covered. Let the etch primer dry for an hour or so and then hit it with the engine paint, using light coats with 20 minutes "flash off" time between coats to build it up to a nice deep finish, without lots of runs or sags.

Let it all dry for a couple of days before you start it for the first time, and make sure you don't spill any solvents on it, like gas, for instance. When you do fire your engine up for the first time, start it and run it for a few minutes until it's at operating temperature, then shut it down and let it sit for an hour or so, so the new paint can "bake" onto the engine. Do this a couple of times if you like, the harder the paint is before you subject it to road grit, stones, road salt, bugs etc, the more chance you'll have of it still looking good in years to come. Cheers, Terry. ;D 
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Offline nayto550

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #8 on: March 17, 2012, 06:02:04 AM »
Terry, you say to run the engine to bake the paint.  I was looking to paint my engine while it is completely disassembled, so any tips on temp and times for baking high temp engine enamel in an oven?
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Offline Terry in Australia

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Re: Is stripping absolutely necessary as a prep to painting?
« Reply #9 on: March 17, 2012, 01:35:17 PM »
Ha ha, I didn't mention the oven, because for most married men, the oven is out of bounds............

I actually have an industrial oven in my garage though, so I do bake the paint on before re-assembly. Use the same directions as above, let your cases dry for an hour or so at room temperatuture, (so the paint gets a chance to flow out and settle, and it allows the solvents to evaporate, so less chance of it exploding) then put them in a cold oven and set it to 200 deg F. Let it bake for a couple of hours, then switch the oven off and allow the cases to cool in the oven.

Engine enamel really need heat to cure it, and without heat it's a lot more susceptible to damage than regular paint, so if you can get hold of an old electric oven (I bought a small bench top oven on ebay for 2 bucks, and was given the big industrial oven for free) you'll get a nice, durable finish finish. Cheers, Terry. ;D   
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)