POR-15 Surface Prep Question

[Traveller]

Hi All. I have a quick (and likely stupid) question...

I've never used POR15 before, but ordered the kit from amazon which arrives today. I see that it includes some kind of metal prep / etching primer as part of the kit. I plan on using this to paint the cast section of the IRS differential tonight. My question is that the differential (bought from FFR) came painted from the factory. I assume I need to strip that paint off to get the POR products to adhere properly. Is that correct?

Also, is there a recommended brand of clear topcoat? I see POR makes one, but I did not purchase that.

Thanks,
Jason

[DadofThree]

I'm not going to be able to help too much, but I thought I'd chime in.

First, please don't apologize for asking questions. We've all learned as we went along. Questions are good.

Building this car was my first time with POR-15 too. Now I use it for a lot of things. I purchased the spray can, and just spray it on top of whatever I'm painting. I haven't used the primer. My rear was from a junk yard (Not IRS) and it had a lot of surface rust. I cleaned the entire rear end with brake cleaner, and sprayed several coats of the POR-15 on it, and it's still on there just fine. But mine really needed it, and your differential has been newly painted (if I understand correctly). It doesn't come in contact with anything during it's life (hopefully), so I wonder if you need to paint it again. If you're happy with the appearance of the painted differential and you want to put clear on top of it, just add several coats of POR-15 clear coat on top of the already painted item.

HTH

[edwardb]

First I've heard of the IRS differential received painted. Are you sure? Would be interested in a picture if you could post one. Whether the iron case (which is the one I believe FF supplies) or the aluminum case, every one I've seen and used was unfinished. The iron case version turns rust orange almost immediately, which is the reason many of us paint it. If yours is already painted, maybe don't even mess with it.

[Papa]

POR means Paint Over Rust. Wire brush the loose stuff of whatever you plan to coat with POR-15 and make sure there isn't any grease, oil, silicone, etc. and brush or spray the stuff on. It's very forgiving and as long as you don't try to recoat it when it's tacky, will self-level to a nice smooth finish. You should use top-coat if the area you are treating will be exposed to sunlight as POR-15 has no UV protection and will fade. I've never used primer or top coat and everything still looks like it did the day I applied it.

P.S. wear gloves! If you get this stuff on your skin, plan to wear it for a couple of weeks!

[doddmoore]

POR is for Paint over rust as others have said. I am currently using it and have found if it does not have rust on it, as mine does not, the surface should be cleaned really well then scuffed really well. It will need something to adhere to and the scuffing gives it better adhesion. I tested with the scuffing and without and the scuffed was MUCH better.

[Traveller]

First I've heard of the IRS differential received painted. Are you sure? Would be interested in a picture if you could post one. Whether the iron case (which is the one I believe FF supplies) or the aluminum case, every one I've seen and used was unfinished. The iron case version turns rust orange almost immediately, which is the reason many of us paint it. If yours is already painted, maybe don't even mess with it.

Pretty sure... Here ya go:
https://thefactoryfiveforum.com/attachment.php?attachmentid=114445&d=1568680972

[Papa]

That looks like undercoating. I'd probably just install it as is and call it done.

[edwardb]

Agreed, that's a factory coating. Evidenced partly by the factory handwriting on the case. Same as on previous NIB versions. Interesting change from our friends at Ford. Like I said before, the main reason most of us were painting them was to hide the orange rust that starts the day after they're built. I'd be inclined to leave it as is as well.

[VAHokie]

Great timing on this post as I was planning to POR15 a few things this weekend including the diff. Mine came with the undercoating as well and I had the same question, so thanks for beating me to the punch! Would duplicolor's engine enamel gloss clear be sufficient or should I look to something else to seal it up?

[DavidW]

This would've helped but looks like some insight has eliminated the need.

FYI thinning out the second coat of POR 15 really makes a nice smooth finish coat, similar to a powder coat finish.

https://www.por15.com/POR-15-Technical-Information_ep_62.html

[KenWilkinson]

Another similar product. Also in silver

http://www.magnetpaints.com/underbody.asp

Chassis Saver

[j.miller]

PREP ! That's funny. Once you use it you will find that it sticks to EVERYTHING ! Were rubber gloves, put down cardboard, take off your shoes before you go in the house.....etc.....etc....etc...da bat

[Traveller]

I took everyones advice and left the undercoat on it. I cleaned it up with some acetone and hit it with some clear coat (the duplicolor ceramic that you mentioned) and it looks great!

Thanks all.


Great timing on this post as I was planning to POR15 a few things this weekend including the diff. Mine came with the undercoating as well and I had the same question, so thanks for beating me to the punch! Would duplicolor's engine enamel gloss clear be sufficient or should I look to something else to seal it up?

[Traveller]

Love it... Looks like I wont be using the POR15 this time, but I am anxious to use this stuff.
PREP ! That's funny. Once you use it you will find that it sticks to EVERYTHING ! Were rubber gloves, put down cardboard, take off your shoes before you go in the house.....etc.....etc....etc...da bat

[bcshannon5448]

The Jeep frame that I painted with POR15 was sandblasted with no other prep and it still looks great. I did top coat on any surface that saw direct sun.

[GTBradley]

Mine was the same, I just clear coated it and moved on.

https://thefactoryfiveforum.com/attachment.php?attachmentid=100771&d=1547527030