Overthinking

Well this is a really interesting thread. I painted my ‘72 TR6 this past summer and had a couple of problems but got it all sorted and I’m kind of proud of how it turned out. However, I need some advice for the next one...
When I sanded the tub and all the panels I used 80, then 120, and so on. Reading this thread I’m getting a feeling that you don’t have to use every grit consecutively but can skip a grit or two as you climb the ladder. Is this true or am I wrong?
 
Well this is a really interesting thread. I painted my ‘72 TR6 this past summer and had a couple of problems but got it all sorted and I’m kind of proud of how it turned out. However, I need some advice for the next one...
When I sanded the tub and all the panels I used 80, then 120, and so on. Reading this thread I’m getting a feeling that you don’t have to use every grit consecutively but can skip a grit or two as you climb the ladder. Is this true or am I wrong?

Starting with 80 you can safely go to 180, from 180 to 320, from 320 to 600 wet. Most collision shops these are the only grits they will stock.(not including color sanding) You can do it any number of ways though depending on what you are trying to do. Blocking poly primer 120 or 150 would be good grits to do the initial blocking with. Lots of guys like 400 wet as a final sand especially with solid colors. Color sanding by hand with the finer grits it's helpful to go with the consecutive grits like 1000, 1200, 1500 and 2000.
All just a matter of preference through experience.
 
Would you need to prime in between these grits to fill the scratches? Or as long as you guide coat and have enough material can you just keep going until all scratches are gone? How do you know you have enough material to block a panel with another grit?
 
When I sanded the tub and all the panels I used 80, then 120, and so on. Reading this thread I’m getting a feeling that you don’t have to use every grit consecutively but can skip a grit or two as you climb the ladder. Is this true or am I wrong?
What material are you sanding? 80# to sand 2K is a little too rough, IMO. You will go through almost immediately, and not have enough material to get those scratches out. Poly primer it would be ok, but I still usually start with 120#. If spots of the underlying epoxy are starting to show, no reason to go to the next grit without applying more material. For instance, you block with 120#, apply guide coat, block with 180# but spots of epoxy start to show through. Stop and apply 2-3 more coats. Then you can start with 180# lightly, guide coat, then block with 320# until no 180# scratches show. If no sand throughs, (or minimal), guide coat and sand with 600 before sealer.
 
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I gotcha, Chris. I was just wondering what material he was sanding. He stated on his previous car, he started with 80# and worked his way up. Got to have a lot of material to start with 80# and not go through before switching grits. I've gotten to where I like 120# even on filler. The scratches come out so much easier with 180#, and it cuts almost as quick.
 
I’m curious, how many rounds of primer and blocking are you doing on an average restoration? I did two coats of epoxy, two coats of slick sand and blocked, two coats of 2k and blocked. I think I may need one more round of 2k and blocking with 180 before I can reprime and do my final 320 sand and 600 for sealer. Does that sound crazy? That’s five primer spray sessions! Its an old beat up truck.

Also, do I have to follow the paint instructions to a T? The instructions say P400. I like to use dry 600 with my mirka vacuum dustless blocks. Is that ok or does it have to be 400?

Thank you for the great help.
 
On restoration work, you have to learn to work, form and replace metal. The amount of work depends on the shape of the vehicle.
My process is to take pictures of the entire vehicle. I mean detailed pictures or the problem areas first, then each step of the disassembly so I know where the wires run, how the linkages were installed, etc.
While doing this I am making lists. Things that need replacing, rust that needs to be removed, and the color certain things should be painted, etc.

Once it is completely stripped to the shell and all the paint is off, I normally prep and shoot two coats of epoxy. If there is a lot of rust, I may cut that out and weld in good metal prior to shooting epoxy. Either way, the goal is to get the panels rust free and as straight a possible.

Remember this is what you will be actually painting so taking a little more time getting the foundation right will help in the following steps.

Each step from there has the same goal, get the panels as straight as possible. The painting is the easy part.
 
On restoration work, you have to learn to work, form and replace metal. The amount of work depends on the shape of the vehicle.
My process is to take pictures of the entire vehicle. I mean detailed pictures or the problem areas first, then each step of the disassembly so I know where the wires run, how the linkages were installed, etc.
While doing this I am making lists. Things that need replacing, rust that needs to be removed, and the color certain things should be painted, etc.

Once it is completely stripped to the shell and all the paint is off, I normally prep and shoot two coats of epoxy. If there is a lot of rust, I may cut that out and weld in good metal prior to shooting epoxy. Either way, the goal is to get the panels rust free and as straight a possible.

Remember this is what you will be actually painting so taking a little more time getting the foundation right will help in the following steps.

Each step from there has the same goal, get the panels as straight as possible. The painting is the easy part.
Great advice. I inherited the truck from my grandpa after he passed and it was in little pieces already. I feel like I’ll need to do this restoration again in 15 years to get it really perfect. I’m aiming for as close to perfection as I can get but since this a first attempt I am making mistakes then looking back and realizing I could have done thing’s better.

I put two more coats of 2k on the fenders before church this morning. I came back and hit it lightly with 320 to open it up and they blocked out perfectly. How long should I leave in the sun before finishing in 320 and 400 wet and sealer? I’m trying to prevent shrinkage.
 
Well, here's the result. I ended up wet sanding with 400 before reduced epoxy. I was religious with my guide coat and watching sand scratches this time. I think it paid off. It's straight as can be and I see no scratches. A few larger pieces of curly black threads.... My guess is it came from my brilliant idea of carpet in my booth. The color is called ice blue but is actually green. Thank you for all the advice!

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I would like to revisit an earlier part of this thread with a few questions. My intention is to use a filler (probably 3M 31131 Platinum Select) and SPI Epoxy as high-build primer to do the bodywork. My goal is to keep the material thickness to a minimum. Guide coat is given at every step below.

- It has been advised to start sanding the filler with 36/40 grit. Should this step be done with a DA or by hand with a long block?
- Is epoxy, filler, 40, 80, reapply filler, 80, 150, reapply filler, 320, epoxy, a sound recipe?
- What should my sanding process/steps be for the epoxy and subsequent filler if needed?
- How long should epoxy cure before applying filler?

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Emil
 
I use the 1171 which I've heard is similar to what you are using. I normally start with 80 grit. It's already so smooth that 36/40 is not needed. However you need to make sure it's flat before going to 180 or 220.
 
If you know you will be reapplying filler, no reason to waste time sanding finer than 80#. I always start with 80# and finish with 180# before epoxy. No reason to go finer. Normally, I block the epoxy with 180# to show lows, repair with filler and finish with no scratches heavier than 180# left. Epoxy and repeat until it blocks with no lows showing. Block with 320, wet sand with 400-600, seal and paint. Wait at least 24hrs. to apply filler, 48 hrs. is better.
 
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