Yes, that old game. I bloody hate rust, but unfortunately, I have found myself the proud owner of a car with some. Not bad, but in a bad place.
Before we start, a short word. PPE. Wear it. Almost everything in this post (and most other posts) will kill or seriously maim you if you don’t wear the correct Personal Protective Equipment. I can’t stress it enough, use a quality mask, ear plugs/protectors, gloves and safety glasses/goggles. You don’t want to breathe any of this in or get it in your eyes. When welding use the appropriate face/eye protection, gloves and fireproof clothing (and check your surroundings). Stay safe.
Another word; I am not a professional. I have never done panel/body work/paint before (but know my way around a welder in a basic sense), so don’t take what I have done as a guide. If in doubt, consult a pro.
It all started when I got home and noticed these little pimples in the paint. Sadly I didn’t notice them when viewing the car because it was bucketing down and quite frankly I wasn’t paying attention, and these aren’t really known for rust.
I got bored one day and decided to see what the pimple was hiding. Turns out the pimple is lifting bog, and under that is very thin metal. So thin, your screwdriver pokes a hole in it. Now I’ve done it. Well, since I have one hole, why not two?
Rust here is very bad news. A car cannot have rust within a certain distance of the A Pillar, so there was no way it would pass a WOF like this (and the WOF has just expired).
I had two options. One, take the car to a man and get it fixed. Two, be that man and fix it myself.
Option two was the way forward, of course, because hey, ain’t no learning experience like being thrown into the deep with lead weights on your feet. Plus, this is a “cheap” car, I don’t want to have to pay someone too much to fix it, and it doesn’t have to be perfect, just strong.
I sourced an old bonnet from a friend and set to work cutting it up to calibrate and practice with my welder. I haven’t touched this at all since I welded the handbrake back to the floor of the Mini, over two years ago.
No, it’s not pretty, but it took a lot of dialling in to get the flux core wire (hollow wire with flux inside to shield and protect the weld during welding) to play nice with thin panel steel. I got there in the end, and a couple more practice patches meant I was ready to give the real job a shot.
First I had to remove the old paint and bog to see what I was working with. I grabbed one of these stripping discs for my grinder and woah its amazing for this sort of work. No sparks, no damage to the metal, it just made the paint and bog suddenly disappear.
I then got out the old poky tappy slag hammer, and poked more holes in it. I had to find solid metal as I couldn’t weld good metal to thin crappy metal. I poked a lot more holes after these photos were taken.
And then out came the welder. Before welding, the windscreen and side windows were covered with wet sheets and rags to protect them from welding spatter. The previous repairer didn’t do this, and there is a couple of spots of welding spatter etched into the side window glass.
With panel steel you can’t just run a nice tidy bead around the edges, you have to do a series of small tack welds all around it and stitch it in. If you weld too much it will overheat the panel and warp. To keep the heat down I used a combo of an air blower on my compressor and cold wet rags. With flux core, I also had to keep stopping to wire brush the welds to clean them (as flux leaves a residue that will make any welds that touch the residue contaminated). I wouldn’t do this job with flux core again, its way too finicky. A real PITA.
Also, note that random screw. I had to screw this into the panel in order to attach the negative clamp for the welder as there was no other good area to use. Its easier to drill a small hole, screw that in and then plug it with weld later than to mess around with a bad ground.
The inside of the panel was full of chunks of flaky rusty rubbish. I vacuumed it out both times I opened the panel up and treated the inside of the panel with rust convertor.
This is the panel I cut out. Note the unprotected metal on the back, as well as the big lump of weld where someone had just pointed the nozzle into the hole in the panel and filled it with liquid metal.
Obviously the flat patch on a curved panel was no good, I’d need as much bog as the previous repair did to just level that out, so with some careful hammering, I curved the panel to fit better. The edges were also cleaned so I wasn’t trying to weld on paint. Ignore the ground down spot in the middle, this is what happens when the bench grinder snatches the patch out of your fingers and jams it between the grinding wheel and rest platform. Oops.
Anyway, it was time to start gluing this patch in place with metal. On this one instead of just wire brushing the welds as I went, I chose to grind them down as I went, which made it much easier to spot holes and gaps I needed to fill, as well as reducing the amount of work on the final tidy up. Here is about a quarter done
The next day I was planning on cleaning the metal back and applying filler. This was delayed slightly by my discovery that the windscreen was cracked.
A small blob of superheated welding spatter had somehow got under two layers of sopping wet rags, and a wet sheet, to land on the windscreen. This concentrated heat causes it to crack.
Long story short, you fill the crack with the resin, push the air out by gently pressing on either side of the crack from the inside, and then lay some clear strips over the crack/resin and leave in the sun for 10 mins to cure. A razor is used to shave the excess dry resin off, leaving a clean and smooth surface.
The results were actually quite impressive. You can see a thin line where the crack was (especially in the black surround), but the crack has no depth to it now. It is really hard to photograph though
A+ would use again. Not sure how it goes on chips as I haven’t tested that, but it certainly works on cracks.
So moving back to the panel work, it was time to ice a
cake panel. I started by using a 30 grit flap wheel on the grinder to clean the areas up and then used some 80 grit to key the panel. Then I slapped the bog on.
Having never used bog/filler before, this was a bit of an experience. Lots of Youtube videos and googling pointed me in the right direction, and it seems to have worked. One trick I was told, was that if you don’t have a fancy non-stick board like the pros use to mix and spread the filler, stick a sheet of baking paper to a board. The filler won’t stick to the baking paper or soak in, and it’s much easier to work with.
Once the filler was dry, I started to sand it back. Using an 80 grit on the orbital sander I knocked the majority of it back, and then used 80 grit by hand to shape it more. I found this a hugely messy job with the orbital until I realised my workshop vac fit the little dust outlet on the sander (it usually has a small filter bag attached). This meant most of the dust got vacuumed up as I went, and reduced the dust a lot.
This was a really hard area to shape. There are curves in so many directions all joining here, but I did the best I could with the skills at hand. A final sand with 300 grit to smooth off the filler and we were ready for primer.
After a few coats of primer, the masking was removed and the primer was left to cure overnight before sanding.
As you can see I also sanded the clear next to the primer as this was covered in old overspray from the previous repair. In hindsight I think this was where I started to go wrong. I could have got away with not sanding this and painting a much smaller area as I had intended (only planned to paint as far as the primer, into the ditch).
I could already see the paint was a slightly more red shade but hoped it would dry more orange. I also had issues with the spray can spitting drops of paint. Thankfully more coats seemed to cover these up.
The coverage was good, there was no sign of the primer through the paint and it looked even.
Unfortunately between the first and second coats I opened the big garage door to try and vent more fumes (the clearcoat is very cloudy), and the humidity in the garage spiked to about 88%, which is way too high. This lead to bloom, and a cloudy/milky finish to the clear. I was not happy.
Youtube and google told me I might be able to save it with a heat gun on low, to warm the paint up and the moisture might clear. Now, this DOES work, but you have to be bloody careful or the paint can and will blister.
After causing a couple of small blisters I called it quits; I couldn’t risk more damage to the new paint. I’d just have to see if the rest of the bloom clears by its self.
There was one step left that might save it. Wet sanding.
I left the paint to dry for over 24 hours and then backed the car into the drive for its first wash since I bought it.
It cleans up pretty well really. It was good getting all the dust off, as it was filthy from all the grinding/sanding. No signs of any wax though, not a single bead in sight. I also used a clay cloth on the paint as it felt like sandpaper. The paint is nice and smooth now.
So now it was time to sand the paint. I set about wet sanding with various grades from 1200 grit to 5000 grit. I had a few issues, like some paint in a certain patch lifting loose (where I had painted over the original paint with minimal prep), and a couple of patches where I burnt through on an edge. Once again, in hindsight, try to minimise the amount of sanding on the original paint as its really hard to polish out the sanding marks afterwards. A stronger cutting compound would help, but I only have Ultimate Compound.
After wet sanding and drying off, next was to machine polish the paint to bring back the shine.
This is the end result. It’s really obvious where the repair is as the colour is quite different. I should have stuck to my original plan and only painted as far as the gully that runs the length of the roof. I chose to paint further out to try and correct some of the overspray from the last repair, which I could have just fixed afterwards anyway.
I do need to keep reminding myself that it doesn’t need to be perfect though. This isn’t a show car, it’s a $1200 beater that I’m going to modify and beat on. The goal was to fix the rust, not fix the paint.
I couldn’t stop there though, since I had a nice shiny roof the rest of the car looked really dull. So, I machine polished the whole car (except the bonnet, which has no clear left to polish). It’s bloody shiny now. A good coating of wax, all the windows cleaned inside and out, and it was finally time to kick the car out of the garage.
In the natural light, after the polish and wax, the colour difference isn’t actually too bad. You can notice it if you’re looking, but otherwise you might dismiss it as a shadow or reflection. Its miles better than what was there, even without the rust the paint was a worse match and had no gloss or shine to it.
I wrote most of this post in advance, so today was WOF inspection day, and by some miracle (not really, its a beast), the mighty Corolla passed with only an advisory for surface rust on the fuel pipe under the car (which I will treat and protect). The inspector was very impressed with the car and had only good things to say.
So with another 6 months of motoring on the clock, it’s time to open the wallet again and spend more money. Now its time for the expensive bits. With any luck, we should be ready for the first track day at the end of January.