Please explain RAS 115 abrasives

[John Stevens]

For the RAS 115, the Cristal abrasives go from 24 to 80 grit, and the Rubin go from 24 to 180.  Coupla questions 'bout that--

The Cristal would be better than Rubin for removing paint, right?

Would I use only one grit to remove all the paint?  For example, I wouldn't start with 24, remove half the paint, and then change to 36, 50 and finish with 80, right?

For latex paint, how do I figure out which grit to use?  Are there situations when 24 is better than 80, and vice versa?  Are there situations when 36 or 50 is best? Do I just have to try it and see, or are there rules of thumb to follow?

For removing latex paint on trim, I'm assuming that I'd remove all paint with the the RAS 115 and then sand the bare wood smooth with a random orbital sander (ROS 150 or RO90).  Correct?

What kinds of applications would call for the RAS115 with the 100-180 grit abrasives?

Thanks in advance for your help.

Regards,

John

 

[WarnerConstCo.]

I start with 36g Saphir.  I sand through 50 and 80g Rubin then switch to 100g on my rotex in rotex mode. 

I hardly switch to random orbit or break out the ets anymore except for finishes.

 

[ajones]

Hi John

I think cystal is for paint,  use the finest grade that removes the material at a rate that you are happy with,with out damaging the substrate, Its a case of suck it and see, no hard and fast rules with paint/finish removal

 

[Administrator_JSVN]

John,

Cristal can be used on bare wood or stubborn build ups like paints. It has a coating that's going to help prevent clogging. Rubin is really designed for bare wood only. That doesn't mean that you can't use it as a general abrasive for just about anything, it just means that's what it does best.

Your grit is going to determine how quickly you're going to cut through that paint. The lower the grit, the faster you're going to remove paint. But... the more severe the scratches will be in the underlying material. The trick is to find a good compromise between paint removal and surface quality. If you have multiple layers of thick latex paint, I'd go with something in the 24-50 range. If you only have one or two layers of paint, I'd start between 50 to 80.

You could use the RAS with those higher grits when you want more finesse with the material removal.

If you're going to repaint, you'll want to clean up the surface with a higher grit, up to 150 give or take. Using a random orbital sander would provide the best results.

I'm sure some members who have the RAS can also add their experiences (looks like there already are some as I typed this). I've really only used it for stripping thick paint off of siding.

Edit: Darcy's using the Saphir and that stuff is amazing and lasts a very long time without loosing its bite. I personally would use this over Cristal based on my own experiences.

There's also a chart here that explains the general uses for each type of abrasive in simple terms: http://festoolownersgroup.com/festool-tools-accessories/festool-abrasives-details/msg152602/#msg152602

Shane

 

[John Stevens]

Thanks guys for your advice, especially Shane for replying on the weekend.

Regards,

John

 

[worldburger]

Between Saphir 24, 50, and 80, here are my observations.

This is all on a 100+ year old house with perhaps 5-8 layers (various paints, primers). The primary and secondary layers (closest to the wood) were a good test for this (they were incredibly hard).

24 was disappointing. Perhaps my technique needs work, but my observation was with the grit so coarse the grains are very tall and spaced wide, not giving enough surface area to lift an entire layer of paint efficiently. It seemed to require a lot more pressure than the 50 to remove a comparable amount of paint. However, 24 was at times good at lifting up loose layers of alligatored paint (acted almost like a scraper).

50 was quicker than 24 at removing the paint. It required very little pressure for the results. With a speed setting up to 4~4.5, it would remove everything I put under it. >5 it gummed up. Very efficient.

80 was great for finesse as Shane says and also for lighter or fewer layers.