Correct way to prep this for spraying (with pics)

[holy85]

Hi everyone,

This is my first post here.

At the moment I'm working on restoring a sunroof, which is really rusty in places. What Would be the best way to tackle this rust to get it ready for paint?

So far I have scraped off and sanded down as much of the rust as I could and then apply this rust remover product below.

Cheers

 

[irondarren]

Rub it down with wet and dry. do you own a small angle grinder? they do wire wheels that fit 4.5 inch angle grinders, basically wire brushes that fit angle grinders. Great for rust removal on anything metal

 

[holy85]

I used the wire brushes which connect onto a drill instead of an angle grinder. It took loads of loose rust away. But it don't completely remover all the rust. I'm guessing this will give problems if I were to paint over it like this?

 

[irondarren]

Yes it is best to remove all the rust, the wire brush that fits the angle grinder is more aggressive than the drill type due to its faster speed. I guess the other alternative is rust killer, which is really i guess what the hammerite stuff you are using is.

 

[Chipper]

I would say a mix of things; get the paint off, then various wire brushes, paper, even needle files for tight places.

Not used that gel but guess it's similar to the Bilt-Hamber one, which is good stuff for getting rust out of pits or awkward spots.
I tried a Hammerite acid for submerging parts recently btw, supposed to be diluted 1:9 (think either phosphoric or oxalic acid); it was pretty useless at 1:9 but good when stronger.

Could always have it blasted.

What sort of paint will you be using?

 

[Chickenjohn]

Wire brush on grinder to get rid of the worst of the rust and then make up a 5-10% solution of citric acid in hot water in the bath (or other container), let soak over night, dry, sand and etch prime and paint.

Either that DIY route or have the item sandblasted or dipped.

 

[holy85]

I would say a mix of things; get the paint off, then various wire brushes, paper, even needle files for tight places.

Not used that gel but guess it's similar to the Bilt-Hamber one, which is good stuff for getting rust out of pits or awkward spots.
I tried a Hammerite acid for submerging parts recently btw, supposed to be diluted 1:9 (think either phosphoric or oxalic acid); it was pretty useless at 1:9 but good when stronger.

Could always have it blasted.

What sort of paint will you be using?

Thanks for the reply

I've got u-pol acid 8 primer which I will use after. Then I will be using 2k primer and base coat.

 

[holy85]

Wire brush on grinder to get rid of the worst of the rust and then make up a 5-10% solution of citric acid in hot water in the bath (or other container), let soak over night, dry, sand and etch prime and paint.

Either that DIY route or have the item sandblasted or dipped.

Thanks for the reply.

is citric acid same as baking soda?

cheers

 

[Chickenjohn]

No, its completely different to baking soda which is basic in terms of chemistry wheras citric acid is an acid. Citric acid is found in fruit (lemons etc) and is non toxic and a biodegradable natural product.

It is very good at dissolving rust and leaves the steel unharmed if used overnight. Google it- available cheaply on the net in multi KG quantities.

 

[holy85]

Cheers mate, had a look on ebay for it. It's definatley worth a try at that price.

http://cgi.ebay.co.uk/10-x-10g-Packets-of-Citric-Acid-Descaler-Avent_W0QQitemZ290290724182QQcmdZViewItemQQptZCoffee_Machines_Makers?hash=item290290724182&_trksid=p3286.c0.m14&_trkparms=72:1683|66:2|65:12|39:1|240:1318

 

[Chipper]

If you can do 2k, another choice is 2k epoxy primer and not worry about minute spots of rust (get rid of as much as poss of course). The epoxy can take it. That's my choice, I don't like etch but as always there's more than one way to do things. Epoxy is used on ships and high-dollar hot rods, and also acts as a sealer. Seems to be popular in the states where etch is more popular over here.
If yr doing 1k basecoat, and going to 2k clear over the top, there's a finite time window for getting the clear on or it won't adhere well ('scuse me if you know this already like).

 

[Chickenjohn]

You can get Citric acid cheaper than that in KG quantities if you have a lot of items to clean of rust. You could get a large plastic bag and use that as the "tank" to immerse the sunroof in. Get rid of most of the rust by mechanical means and then soak for 24hrs, it also helps to agitate the rusty areas with an old tooth brush or wire brush. First picture is of rusty Morris Minor door bottom immersed in citric acid solution in the bath. 2nd picture and the rust is all dissolved!

 

[BMAK]

Cheers mate, had a look on ebay for it. It's definatley worth a try at that price.

http://cgi.ebay.co.uk/10-x-10g-Packets-of-Citric-Acid-Descaler-Avent_W0QQitemZ290290724182QQcmdZViewItemQQptZCoffee_Machines_Makers?hash=item290290724182&_trksid=p3286.c0.m14&_trkparms=72:1683|66:2|65:12|39:1|240:1318

Just make sure you dont get in trouble with the police, recieving little 10g bags of white stuff through the post

 

[holy85]

You can get Citric acid cheaper than that in KG quantities if you have a lot of items to clean of rust. You could get a large plastic bag and use that as the "tank" to immerse the sunroof in. Get rid of most of the rust by mechanical means and then soak for 24hrs, it also helps to agitate the rusty areas with an old tooth brush or wire brush. First picture is of rusty Morris Minor door bottom immersed in citric acid solution in the bath. 2nd picture and the rust is all dissolved!

Good idea that, cos I'm sure i'll be doing more de-rusting like this in the near future.

 

[holy85]

If you can do 2k, another choice is 2k epoxy primer and not worry about minute spots of rust (get rid of as much as poss of course). The epoxy can take it. That's my choice, I don't like etch but as always there's more than one way to do things. Epoxy is used on ships and high-dollar hot rods, and also acts as a sealer. Seems to be popular in the states where etch is more popular over here.
If yr doing 1k basecoat, and going to 2k clear over the top, there's a finite time window for getting the clear on or it won't adhere well ('scuse me if you know this already like).

This is defiantly useful.

I remember asking at my local paint supplier for epoxy primer when I first researched into the area of paint, but unfortunately my paint supplier didn't supply that. Instead he sold me 2k Acrylic Primer?.. which I'm guessing is a cheaper/universal primer in comparison?

 

[rtcosic]

For parts that can be removed form the vehicle like this I like to use electrolytic rust removal method.
Use Google or look here for basics:
http://stovebolt.com/techtips/rust/electrolytic_derusting.htm
http://www.antique-engines.com/electrol.asp

I thought I recalled a thread on this Forum on the subject, but couldn't find it.

 

[Chipper]

2k is two-pack, i.e. mix a hardener with paint, then thinners (so three components). hardens by chemical action with the hardener (isocyanates, nasty, needs proper safety kit for spraying). If it's acrylic you've got I think it must be 1k, i.e. paint + thinners, no iso hardener.

Some people do seem to call 1k and even celly 'two pack' meaning paint+thinners but that's not really right, two-pack is a different animal.

So if you got paint+hardener then it's 2k, if not then it's 1k.

 

[Chickenjohn]

You really need to remove all the rust before priming or it will come back and bubble through, epoxy sealer primer or not. Rust is like cancer for steel cars ;-(

 

[madkayaker]

maybe try one of the dipping solutions on here

 

[Chipper]

I've done a fair few things in epoxy over minor rust, and none have had the accursed stuff show through. It's always best to get it all off for sure, and def anything even remotely loose, but so far I've not had probs coating over minor rust. It does seal pretty well, our trailer got a quick 'n dirty coat in it and lived outdoors for 3 yrs with only very minor rust after that, although it does degrade in UV so it's just bin topcoated.
For holy85 it sounds like 2k is not an option though so get that grot gone...