Hand Cutting & Polishing out fine sand marks

[Manix]

I have interior car items that can`t be machine worked & that are polyurethane & 2k urethane. I have sanding out deep scratches with fine sand paper & finished on the highest grit I can which for me is up to 7000P.
I tried polishing up to a high gloss by hand using an orange medium cut pad with M105 & after 8 hand cuts I only got about 80-90% of the sand marks out.

I don`t see the point in going yellow hand pad as my orange has hardened up now from all the uses & cuts slightly more than the yellow. I noticed no matter how much you work M105 & M205 they never really dry up & haze like they do very quickly with wool pad on rotary. After a minute or so of solid hand circular motion I wipe off the old compound with tissues & then apply some more, & frequently wash foam pad after it gets clogged.

Should I be using a different brand compound for hand? because this kills my hands how much hand work you gottta do.

Even the polishing stage with M205 takes at least 4-5 solid hard sessions before the cutting marks are removed.

Please help, thanks

 

[Accumulator]

Manix- Noting that the Polyurethane/2K Urethane are finishes I have no experience with...

Generally, I suspect you`re switching to a gentle paper (and M105 and M205) too soon. 2K-4K scratches should be very smooth, so much so that you shouldn`t see actual "scratches" without magnification- all you should see is "dull paint" and 7K should be even finer than that. IF you see "deep individual scratches" instead of a uniform haze, you switched to the gentle stuff too soon IMO.

Some sorta-random thoughts follow:

-I`d expect the 7K to leave things basically smooth. I`d expect the previous sanding steps to do that too...by the time you move to maybe 4K all the scratches should be history and all that`d be left for the M105 would be some sanding haze.

-What grit do the residual sanding scratches look like? They oughta look like 7K scratches and those should be very mild. Like...you start leveling with 1500. Then replace the 1500 grit scratches with 2000 grit ones. When all that`s left are the 200 grit scratches, you switch to 4000. If you want to progress to other, finer, grits OK..but 4K scratches aren`t all that bad to remove by hand (on the paints I`m familiar with).

-M105 and M205 should not be worked until they dry out, but rather buffed off while still a bit wet. Remember that those products never break down.

-If there are clumps of dried M105 on the pad they`ll leave "scratches" rather than the "light haze" that M105 should leave.

-Is the pad getting clogged up with product, or cut-off paint? Do you clean the pad out before adding more product? Remember to *NOT* get the pores of the pad clogged up and to avoid those "clumps" of product.

-I wouldn`t switch to the M205 until all you have left to deal with is the light haze from M105 (which should only be visible under certain lighting). If you can see *any* real "sanding scratches" then it`s still way too soon for M205 IMO.

-Doing some of this stuff by hand can take a very long time, even with M105. It might not take several *hours* (not a typo) the way it can with some other compounds, but it can still take a very long time. Especially if you don`t get the vast majority of the flaws out via the sanding first. Ever spend a whole afternoon getting some fingernail scratches out from behind door handles? Yeah...the whole afternoon That used to be common.

-M101 cuts a lot better for me than M105 (including M105 v1.0).

-I`d probably use cotton toweling for the initial compounding, then switch to MF. I dunno if I`d be using foam pads by hand but that`s just me and I *have* used cut-up old pads now and then (just didn`t like it all that much).

But let`s see what others think...again, I just don`t know from sanding out the paint in question.

 

[Stokdgs]

What are the parts from what make and year vehicle ?
What color/s ?
Were these parts just painted ?
Were these parts primed and guide coat blocked before painting?
If so how long has it been since they dried and cured ?
If so, why were they painted with scratches on the surface ?
If not, how did the scratches get in the finish ? How deep are they ?
What are you using to sand the parts with ? Block?? Hand? Fingers? Round tool with sand paper wrapped around it ?
What grit/s sand paper did you start out with? Did you wet sand each time ?
Dan F

 

[Manix]

-What grit do the residual sanding scratches look like?

They look like 2000grit, but really I can`t tell like a pro. They seem to be the next step down from typical wool buffer marks.

-M105 and M205 should not be worked until they dry out, but rather buffed off while still a bit wet. Remember that those products never break down.

Slightly off topic - This seems hard to do with cutting with a wool pad on a rotary as it tends to dry up quick.

-Is the pad getting clogged up with product, or cut-off paint? Do you clean the pad out before adding more product? Remember to *NOT* get the pores of the pad clogged up and to avoid those "clumps" of product.

After 2-3 uses it gets a bit clogged up but no cut off paint or debris at all, its very clean. I don`t clean before adding more product because I don`t have extra pads & after a wash they take a while to dry. I usually clean after 3-4 uses. But I would imagine what ever is on the pad wouldn`t cause the scratches I`m trying to hand cut out, as the marks a linear from sanding & my hand motion is circular.

-I wouldn`t switch to the M205 until all you have left to deal with is the light haze from M105 (which should only be visible under certain lighting). If you can see *any* real "sanding scratches" then it`s still way too soon for M205 IMO.

I agree, I only move onto M205 after all sand marks are gone & just to get the haze of M105 out.

-Doing some of this stuff by hand can take a very long time, even with M105. It might not take several *hours* (not a typo) the way it can with some other compounds, but it can still take a very long time. Especially if you don`t get the vast majority of the flaws out via the sanding first. Ever spend a whole afternoon getting some fingernail scratches out from behind door handles? Yeah...the whole afternoon That used to be common.

Yes. I start going a little crazy thinking the scratch stays the same depth.


Thanks for your help & I will try a cotton material first maybe with M85?

Cheers

 

[Manix]

What are the parts from what make and year vehicle ?
What color/s ?
Were these parts just painted ?
Were these parts primed and guide coat blocked before painting?
If so how long has it been since they dried and cured ?
If so, why were they painted with scratches on the surface ?
If not, how did the scratches get in the finish ? How deep are they ?
What are you using to sand the parts with ? Block?? Hand? Fingers? Round tool with sand paper wrapped around it ?
What grit/s sand paper did you start out with? Did you wet sand each time ?
Dan F

Hi.

They are interior plastics & wood grain on steering wheel etc.
Some are clear over woodgrain & others are black. I can tell they are 2pack coatings as they rub out well.

Since they were factory made I assume they were primed & perfectly flat.
The scratches are probably from something hitting the surface, you can feel with fingernail a little.

I use a soft rubber flexy 3M pad as the parts have curves.
I started out with 2000grit P wet sand & most scratches came out.

 

[Accumulator]

Manix- Thanks for the additional info, some more sorta-random thoughts follow:

-Relying on 2K to level serious scratches can be asking a lot if the scratches are deep
-I don`t use the rotary/wool combo any more, so I can`t really comment on how M106/M205 would work with that, but IME you really need to buff those products off while still wet
-The pad not getting loaded up really astounds me! Since M105 cuts so well, I *ALWAYS*

 

[Accumulator]

Manix- Thanks for the additional info, some more sorta-random thoughts follow:

-I probably wouldn`t assume the factory finish was perfect, but then I can be cynical about stuff like that
-I`d worry (a lot) about removing too much clear on pieces like that. I don`t even correct any such stuff on my vehicles any more as the clear can be thin/fragile
-Relying on 2K to level serious scratches can be asking a lot if the scratches are deep
-I don`t use the rotary/wool combo any more, so I can`t really comment on how M106/M205 would work with that, but IME you really need to buff those products off while still wet
-The pad not getting loaded up really astounds me! Since M105 dries so fast and cuts so well, I *ALWAYS* have old product and cut-off clear that needs cleaned out of my pads. I sometimes think I spend more time cleaning the pads than I do polishing. It would be hard to overstate how big a deal having *CLEAN* pads is for me when I use M105 (or most any other non-diminishing abrasive compound)
-IMO switching from M105 to M85 would be a step in the wrong direction. IF you want to use something else I`d get M101
-That "straight vs. circular" makes perfect sense and tells me that maybe you need to do more sanding with the right grit of paper. BUT...
-A little blob of dried product/cut-off clear can result in a "tracer", a scratch that`s a single, deep gouge in the paint. That can happen during the sanding, and result in something like "2K paper leaving 240 grit scratches", so watch out for that happening too

If I were gonna try to fix that (big "if" as there are lots of flaws I believe people should just live with and I`m almost certain this is in that category), I`d probably try "cross-hatching" the sanding, going perpendicular to the scratches, and see how that goes. If M105 is too gentle for the job things can go haywire; compounding isn`t always safer than wetsanding.

Different people have differing vision, but *I* would definitely be using magnification and some very good lighting for this.

But I can`t help but repeat my concerns about taking off enough clear to fix this. There`s just no way I`d do that unless you`re *ABSOLUTELY CERTAIN* that these pieces won`t get scratched in the future, and IME that`s a pretty tall order even on cars that don`t get used as regular transportation. Voice of experience as I tried to keep my Garage Queens perfect and suffered the consequences in a few cases.

Eh, there are others here who know *MUCH* more about this sort of work than I do, see what else gets posted and compare the responses.