Steps to DIY sanding car back ready for respray....

[silviaz]

20 hours ago, Murray_Calavera said:

Yep, if you are applying filler it sounds like there is something wrong with the body lol. Safe to assume there is going to be a lot of sanding going on if your still applying fillers. 

Picture a perfect bare metal panel, smooth as glass. You lay down your primer, it's perfect. (why are you going to sand it?) You lay down the colour and clear, it's perfect. No sanding at all took place and you've got a perfectly finished panel. 

You won't be chasing your tail, sounds like you were prepping to start laying filler. If your happy with the body after the sanding, there is some bare metal exposed and some areas with primer, no issues at all, start laying the filler. You are safe to lay filler on bare metal or primer (of course check your technical data sheet as usual for what your filler is happy to adhere to). 

This isn't a 100% correct statement. There is primer that is happy to adhere to smooth bare metal. There are fillers that are happy to adhere to smooth bare metal. Just make sure you're using the right materials for the job. 

Typically if you are using filler, you would go primer, colour and clear. I've never seen any instances before where someone has laid colour over body filler (maybe this happens, but I haven't seen it before). So your plan sounds pretty normal to me. 

Thanks for the info breakdown there. I put some body filler today for the first time, surprisingly it went decently smooth lol. I got the ratio correct both times when I did it, and the dent I had is at least 90% better. I put a guide coat and saw lots of black residue left so I'm putting another batch of putty which I'll need to sand off. 

A few dents I fixed up and checked with the guide coat and they were perfect, no black residue left over. Making progress!

Only thing was after I fixed one spot, I put the epoxy primer to prevent rust. Though, I ran out of time for this other dent that I put filler for, I just put filler instead of the primer first. Raining tomorrow, hopefully the rust doesn't start to set it lol.

Edited May 25 by silviaz

[Murray_Calavera]

2 hours ago, silviaz said:

Thanks for the info breakdown there. I put some body filler today for the first time, surprisingly it went decently smooth lol. I got the ratio correct both times when I did it, and the dent I had is at least 90% better. I put a guide coat and saw lots of black residue left so I'm putting another batch of putty which I'll need to sand off. 

A few dents I fixed up and checked with the guide coat and they were perfect, no black residue left over. Making progress!

Sounds good

2 hours ago, silviaz said:

I just put filler instead of the primer first. Raining tomorrow, hopefully the rust doesn't start to set it lol.

Hmm suppose the main thing is, how much do you care about this car? The filler doesn't make for a very good water barrier lol. If there was a tiny little bit of rust forming now, that in 3 to 5 years time becomes obvious under the paint (starts to bubble up), would it bother you? 

[silviaz]

9 hours ago, Murray_Calavera said:

Sounds good

Hmm suppose the main thing is, how much do you care about this car? The filler doesn't make for a very good water barrier lol. If there was a tiny little bit of rust forming now, that in 3 to 5 years time becomes obvious under the paint (starts to bubble up), would it bother you? 

Ah the car is a complete shitbox and not even worth a respray lol, for a professional to do it would probably cost 15k because of all of the dings and stufd but I was keen for a side project. Also solved the problem of being bored haha.

But with the rust yeah I can always fix that in the future, not a huge issue for me.

I found out yesterday that when a dent is created a high spot is created around it (the crown) and to fix it I either need to tap the edges or just sand over it. Which is what made my filler work a bit confusing originally lol.

Edited May 25 by silviaz

[Murray_Calavera]

1 hour ago, silviaz said:

Ah the car is a complete shitbox and not even worth a respray lol

lol nice, I wouldn't worry about sanding back the filler to check for rust then.

1 hour ago, silviaz said:

I found out yesterday that when a dent is created a high spot is created around it (the crown) and to fix it I either need to tap the edges or just sand over it. Which is what made my filler work a bit confusing originally lol.

Yep very much a thing. Personally I don't do the panel beating, its very easy to have a panel beater sort that out for you. If they aren't doing any prep work the actual panel beating generally doesn't take long at all. 

Have you taken before pictures before you started this project? I'd be keen to see the before and afters when you're done.

[silviaz]

8 hours ago, Murray_Calavera said:

lol nice, I wouldn't worry about sanding back the filler to check for rust then.

Yep very much a thing. Personally I don't do the panel beating, its very easy to have a panel beater sort that out for you. If they aren't doing any prep work the actual panel beating generally doesn't take long at all. 

Have you taken before pictures before you started this project? I'd be keen to see the before and afters when you're done.

Yeah I got some before photos I'll show after it's all done and some bodywork progress stuff.

But there's plenty of panels to fix so even if I forgot, plenty of before photos coming up 🤣

[MBS206]

10 hours ago, silviaz said:

I found out yesterday that when a dent is created a high spot is created around it (the crown) and to fix it I either need to tap the edges or just sand over it. Which is what made my filler work a bit confusing originally lol.

Welcome to now being really annoyed at trying to get stretched metal nice and flat again. Or... Fill the low on each side of the high and sand it smooth and forget it has a minor bulge not mirrored in the other panel

[silviaz]

2 hours ago, MBS206 said:

Welcome to now being really annoyed at trying to get stretched metal nice and flat again. Or... Fill the low on each side of the high and sand it smooth and forget it has a minor bulge not mirrored in the other panel

Yeah. Just sanding that high spot until it's flat with the surrounding panel feels lazy to be honest haha but it's a lot simpler to do. I was wondering why I had a wavy panel after the filler and why it went away when I decided to randomly start sanding it away, then I learned about the crown. 

This is that repair, as you can see the guide coat is still in there so I put more filler, which either will fix the problem or I will realise that the other filler might have been gone just had the high spot which wasn't fixed. It's at least 90% better though. Before I did the repair it was a decent sized dent.

I thought about getting my orbital sander and just sanding in 1 spot to get that high spot low as opposed to going outside the panel, then block sanding it the rest so I don't go too far with the orbital sander. This sounds good in theory but we all know how these jobs go 😂

[silviaz]

1 hour ago, silviaz said:

Yeah. Just sanding that high spot until it's flat with the surrounding panel feels lazy to be honest haha but it's a lot simpler to do. I was wondering why I had a wavy panel after the filler and why it went away when I decided to randomly start sanding it away, then I learned about the crown. 

This is that repair, as you can see the guide coat is still in there so I put more filler, which either will fix the problem or I will realise that the other filler might have been gone just had the high spot which wasn't fixed. It's at least 90% better though. Before I did the repair it was a decent sized dent.

I thought about getting my orbital sander and just sanding in 1 spot to get that high spot low as opposed to going outside the panel, then block sanding it the rest so I don't go too far with the orbital sander. This sounds good in theory but we all know how these jobs go 😂

I just realised why you go to bare metal on some sections of the repair after sanding the filler, because those crowns are high spots, they are being sanded before where the actual dent is. Simple but interesting stuff.

I was thinking of starting a new thread, similar to "my build" but more my sanding/respray progress. I can post my progress and mistakes that people can learn from. Providing some value to the forum for once haha.

[silviaz]

I'm having a problem. I think it was mentioned above somewhere but can't see it. 

I'm stuck in the cycle of, sand, filler, low spot again, put filler, sand, low spot again, now i put filler again and a thicker portion which seems to have helped but I got low spots in other areas.

In the image. Circled in red thats where the original low spot was and the shape is the same as the red out line. I've more or less fixed that (still low spot up the top but now I have low spots where the green circled part is. 

Is likely the issue that I didn't start with a course sand paper? I sanded the filler with 240 to reduce the risk of not going to far but maybe the issue is that I'm only taking off enough material to remove some of the filler but not the high spots.

I now started sanding with 120 and I think I'm seeing a difference. I did fix one dent the other 2 are f**ked and seems like I made another low spot which is indicated by the furthest green circle on the left handside.

Any thoughts and solutions?

 

Also second image. All of these rock chips, can they be filled in with primer or do i need to fill them all with filler/putty? So many rock chips on mine lol.

Edited May 31 by silviaz

[Murray_Calavera]

2 hours ago, silviaz said:

Any thoughts and solutions?

Say you've just laid all your filler and your about to start sanding, how large is the sanding block your using? 

2 hours ago, silviaz said:

can they be filled in with primer

Like a high fill primer? Technically possible but would be a nightmare. Just guessing from the photo, but they look small enough that you might get away with using a 1k spot putty. Normally you'd use something like this on pinholes but with the type of project you're working on I'd give it a go. 

[silviaz]

57 minutes ago, Murray_Calavera said:

Say you've just laid all your filler and your about to start sanding, how large is the sanding block your using? 

Like a high fill primer? Technically possible but would be a nightmare. Just guessing from the photo, but they look small enough that you might get away with using a 1k spot putty. Normally you'd use something like this on pinholes but with the type of project you're working on I'd give it a go. 

Just a standard sanding block size. With the rock chipa they are quite small. I sanded them as you could feel the edges. 

[Murray_Calavera]

18 minutes ago, silviaz said:

Just a standard sanding block size

I'm guessing you mean something like this size?

https://www.supercheapauto.com.au/p/bodyworx-bodyworx-hard-soft-sanding-block---70-x-135mm/594184.html?cgid=SCA01100303#srsltid=AfmBOoq_qZTEe3boann9BaHiB2f59dxJlosWLzCr0zm_weHgUlDX-N5f&start=6

20 minutes ago, silviaz said:

I sanded them as you could feel the edges

Are they sanded completely flat?

[silviaz]

11 hours ago, Murray_Calavera said:

I'm guessing you mean something like this size?

https://www.supercheapauto.com.au/p/bodyworx-bodyworx-hard-soft-sanding-block---70-x-135mm/594184.html?cgid=SCA01100303#srsltid=AfmBOoq_qZTEe3boann9BaHiB2f59dxJlosWLzCr0zm_weHgUlDX-N5f&start=6

Are they sanded completely flat?

Mine's a bit bigger at 70x150mm roughly.

The spots are flat, just can feel the edges if I dig my nail into it. I did fix some other other ones by both using my finger to sand that small spot (I'm a bit wary of doing this and creating hot spots and a bigger mess) and I also did sand over it flat and others, but this also worried me a bit because if I create an overall low spot on the panel on paint that is good. 

Correct me if I'm wrong but as long as it's flat even if I can feel the edges, I can put filler because it will all be level once I sand it?

I can see myself going in a circle after sanding guidecoat with 320 grit if for example the panel is flat with my hand but because I sanded the guidecoat I could have created a low spot again somewhere. Unless where I'm going wrong is what I mentioned previously where I didn't go low enough on the grits.

It's 1 step forward and 2 step backwards here haha. I'll probably need to experiment with it more. Last time I go back to bare metal lol.

Edited June 1 by silviaz

[Murray_Calavera]

58 minutes ago, silviaz said:

Mine's a bit bigger at 70x150mm roughly.

Yep I guessed as much. You'll find life much easier with a large block something like this - 

https://wholesalepaint.com.au/products/dura-block-long-hook-loop-sanding-block-100-eva-rubber-af4437

This is a good demo video of something like this in use - 

 

1 hour ago, silviaz said:

The spots are flat, just can feel the edges if I dig my nail into it. I did fix some other other ones by both using my finger to sand that small spot (I'm a bit wary of doing this and creating hot spots and a bigger mess) and I also did sand over it flat and others, but this also worried me a bit because if I create an overall low spot on the panel on paint that is good. 

You have turned your small rock chip holes into large low spots. You'll need to fill and block these low spots. 

1 hour ago, silviaz said:

Correct me if I'm wrong but as long as it's flat even if I can feel the edges, I can put filler because it will all be level once I sand it?

It's always a little hard not seeing it in person, but yes I would go ahead and lay filler over the whole area.

1 hour ago, silviaz said:

I can see myself going in a circle after sanding guidecoat with 320 grit if for example the panel is flat with my hand but because I sanded the guidecoat I could have created a low spot again somewhere. Unless where I'm going wrong is what I mentioned previously where I didn't go low enough on the grits.

It's 1 step forward and 2 step backwards here haha. I'll probably need to experiment with it more. Last time I go back to bare metal lol.

Have a good look at the video I linked, it's a very good example of all the things you're doing. They went to bare metal, they are using guide coat, they are doing a skim coat with the filler and blocking it back. If what you're doing doesn't look like what they are doing, that's a big hint for you  

[Murray_Calavera]

Oh I probably didn't speak enough about the small sanding block for blocking large areas. 

In the video about 3 minutes in, he talks about creating valleys in the panel. This is the issue with using a small sanding block for a large area, it's way too easy to create the valleys he is talking about. With a large block its much easier to create a nice flat surface. 

Hard to explain but in practice you'll notice the difference straight away using the large block. 

[MBS206]

5 minutes ago, Murray_Calavera said:

Oh I probably didn't speak enough about the small sanding block for blocking large areas. 

In the video about 3 minutes in, he talks about creating valleys in the panel. This is the issue with using a small sanding block for a large area, it's way too easy to create the valleys he is talking about. With a large block its much easier to create a nice flat surface. 

Hard to explain but in practice you'll notice the difference straight away using the large block. 

To expand on this to help understanding...

The bigger/longer the block is, the more it's going to work to sit on your far away high areas, and not touch the low stuff in the middle.

When you throw the guide coat, and give it a quick go with a big block, guide coat will disappear in the high spots. If those high spots are in the correct position where the panel should be, stop sanding, and fill the low spots.

However, using a small block, you "fall off" one of the high spots, and now your sanding the "side of the hill".

Your little block would have been great for the stone chips, where you only use a very small amount of filler, so you're sanding and area let's say the size of a 5/10cent piece, with something that is 75*150.

For the big panel, go bigger!

 

And now I'll go back to my "body work sucks, it takes too much patience, and I don't have it"

PS, I thought your picture with coloured circles was an ultra sound... That's after my brain thought you were trying to make a dick and balls drawing...

[GTSBoy]

With stone chips, you really can't just try to fill them. You really have to sand that spot to lower the edges of the chip, so that the filler will end up covering a wider patch than just the chip. Otherwise, you're trying to have a sharp edged paint surface match up to some filler, and they just do not sand the same and you always end up with a noticable transition.

A bunch of adjacent chips should be well sanded back, to round off all those edges, and use a lot (in a relative sense) of filler to raise the whole area back.

[silviaz]

5 hours ago, Murray_Calavera said:

Yep I guessed as much. You'll find life much easier with a large block something like this - 

https://wholesalepaint.com.au/products/dura-block-long-hook-loop-sanding-block-100-eva-rubber-af4437

This is a good demo video of something like this in use - 

 

You have turned your small rock chip holes into large low spots. You'll need to fill and block these low spots. 

It's always a little hard not seeing it in person, but yes I would go ahead and lay filler over the whole area.

Have a good look at the video I linked, it's a very good example of all the things you're doing. They went to bare metal, they are using guide coat, they are doing a skim coat with the filler and blocking it back. If what you're doing doesn't look like what they are doing, that's a big hint for you  

Thanks for all that info.

I thought I heard that the size of the block should be the same size as the repair or is that wrong? Though I do have some long blocks which I can use for the dents in the middle of the panel. The issue is with the ones at the edge of the door and near the grooves.

[silviaz]

5 hours ago, Murray_Calavera said:

Oh I probably didn't speak enough about the small sanding block for blocking large areas. 

In the video about 3 minutes in, he talks about creating valleys in the panel. This is the issue with using a small sanding block for a large area, it's way too easy to create the valleys he is talking about. With a large block its much easier to create a nice flat surface. 

Hard to explain but in practice you'll notice the difference straight away using the large block. 

This is probably what's happened to me. I'll put filler again on my repairs and use the long block and let you know how I go. Fingers crossed it's my last batch of filler lol. I can see that happening where my block dipped at certain points because it didn't cover all the high spots at the same time if that makes sense.

I'm just trying to visualise the fact that with the large sanding block I will be sanding far away from the central dent area and whether that will cause issues or whether that's going to fether out my repairs better.

[silviaz]

5 hours ago, MBS206 said:

To expand on this to help understanding...

The bigger/longer the block is, the more it's going to work to sit on your far away high areas, and not touch the low stuff in the middle.

When you throw the guide coat, and give it a quick go with a big block, guide coat will disappear in the high spots. If those high spots are in the correct position where the panel should be, stop sanding, and fill the low spots.

However, using a small block, you "fall off" one of the high spots, and now your sanding the "side of the hill".

Your little block would have been great for the stone chips, where you only use a very small amount of filler, so you're sanding and area let's say the size of a 5/10cent piece, with something that is 75*150.

For the big panel, go bigger!

 

And now I'll go back to my "body work sucks, it takes too much patience, and I don't have it"

PS, I thought your picture with coloured circles was an ultra sound... That's after my brain thought you were trying to make a dick and balls drawing...

This makes a lot of sense! I just had that realisation a few minutes ago and wrote it above haha. This is a good new discovery. "Sanding the side of the hill" perfect way to put it.

 

😂 😂 

5 hours ago, MBS206 said:

PS, I thought your picture with coloured circles was an ultra sound... That's after my brain thought you were trying to make a dick and balls drawing...

Edited June 1 by silviaz