Sanding advise required.

[julianf]

Years ago I purchased a mirka 650 on advice of Langy. It's a great sander, but I think user error is limiting my progress.


My issue is that the paper gums up fairly quickly (less than 5 mins, I guess?) and then leaves packed dust smears on the job.


I'm thinking I'm doing two things wrong -

Probably not shifting down the grades correctly?
And I have no dust extraction connected.

Which of these do you think is my worst problem?


(As a side note, I use the sander in both paint and wood, and I get similar issues on both, so I don't think it's a substrate issue)

Thank you

 

[richie00boy]

Not using extraction will cause blobs to form on the paper quite quickly. Extractions makes a massive difference both to how long the paper lasts and the quality and speed of finish. Seems a bit daft to buy that expensive sander then hobble it?

However I have found that some papers (particularly red/maroon colour) seems to have the issue much more than others that are specified for paint/bodyshop use. I think the red/maroon ones are for metal only. I think the better ones have some form of coating or the glue is different (stearate?). They are more expensive each but worth it in the long run.

 

[slim_boy_fat]

And I have no dust extraction connected.

Nail > head, as @richie00boy says ^^

 

[Parm]

I’ve done a lot of consultancy work with Mirka, good few years ago now.

use of extraction is essential.

for even better flaw free finishing use their Abranet abrasives. It’s a mesh based abrasive and really allows any dust to be drawn in their sander when connected to extraction.

The Anranet is expensive but lasts much much much longer

it’s a fantastic system

 

[Dcal]

I'm with Parm and use the Mirka sander and abranet sheets.
I've mirka paper as well and it's not at all bad, just the abranet is so much better.

Are you sanding epoxy?
Unless it is fully cured you will get gummy deposits from the top layers, no matter what extraction and abrasive you use.
Only way to stop it is let it fully dry (heat helps) or sand it wet which brings a whole othere set of problems.
Wood can give similar issues dependant on the species.

 

[The_Yellow_Ardvark]

If you are sanding paint you are not letting it dry long enough.
If on wood you are starting to fine.

You can buy a block that will un-clog a belt or pad.
https://www.screwfix.com/p/titan-ab...vQqqas3neSH4DClFC6RoCo2cQAvD_BwE&gclsrc=aw.ds

I have one, great bit of kit to extend the belt life.

Start course and work down. Don't start to fine. You can always add more filler or paint.

 

[brightspark]

If you are sanding paint you are not letting it dry long enough.
If on wood you are starting to fine.

You can buy a block that will un-clog a belt or pad.
https://www.screwfix.com/p/titan-ab...vQqqas3neSH4DClFC6RoCo2cQAvD_BwE&gclsrc=aw.ds

I have one, great bit of kit to extend the belt life.

Start course and work down. Don't start to fine. You can always add more filler or paint.

if your a tight git like me just use a screwed up polly bag and it will do the same thing ive been doing it for years. I have a stack of nylon blocks I can use now

 

[Turbo]

As said, extraction will make a world of difference to your finish & abrasive life. Not to mention your lungs, you will no longer be blowing black snot out your nose afterwards!

Another difference is using decent quality abrasives. I bought a lot of Lidl sanding discs when they were on offer, used them & thought they were ok. I had the opportunity to use some quality siat discs & such a difference they made. Grade for grade they removed paint quicker & more consistently plus they lasted at least 5 times longer so work out cheaper in the long run!

 

[julianf]

Thank you.

The mirka unit was used, and did not come with the extraction port adapter. Obviously I can buy one from somewhere but I've not done so, hence the issue.

I'll see if I can't measure up and find a suitable adapter.

I did have a load of mirka papers and some of the parkside ones. Ill try and find an adapter for the port and get some of the other mirka ones mentioned - thank you.

Substrate -

On paint that has been cured for the datasheet time. And also on wood.

Wood is normally ok until its been oiled. When I say oiled, I mean oiled and left to polymerise or whatever - ie not sanding the next day. The hard "dry" oil seems to clog just like paint on the finer grades.

Maybe I'll take some photos of papers, but I'll also find an adapter for the port as it seems like that is the main issue.

Thanks to all.