Wet or Dry
- Dry advantage - no cleanup and shinier. 
About and Materials
- 9 Days to polish -
- Polished vs epoxy -
- Orbital sander pads - 
- Use 6 of these at one time mounted to a common bar, if you have open space to work with. Each is under 4 lb, so 24 lb total + mounting bar. 3A each for a total of 18A
- Start with bulk grinding of rough spots -  - using a regular grinder:
- Start with 50 grit dry - $10 for one - 
How to Use an Orbital Sander
- 15 seconds per foot travel rate:
- collect dust, so you don't get larger abrasive spots from dust clumps
- Go slow - pigtails will shrink
- Calculations - if 15 seconds per foot, we have 39 passes lengthwise for one passthrough - meaning 1248 feet - meaning 5.2 hours per 500 sf pad. Save 20% by not doing under stairs and cabinets, you have 4.7 hours per pass. 5 sander gang gets that down to 1 hour. Definitely could use a holder for 6-10 sanders. If they can be ganged - that would be awesome.
- Don't skimp on the grits - go up more slowly, which is actually faster.
- Get the dust out - it clogs the sandpaper, and dulls it faster as you need to do more work
- Get extra velcro pads
- Store sander with pad on, so you don't flatten velcro hooks.
- Good thread - 
- Car polisher will work, and so will a variable speed grinder with diamond pads.
- Get this grinder with variable speed can be found elsewhere cheaper. . Pads - . Pad holder - http://www.toolocity.com/4-back-holder-rigid.aspx
- HF variable speed polisher 1 - $44 - 10A - 
- High speed concrete/steel abrasive pads - 4" - only $6 for 5 - 
- 7" diamond pads are much more expensive - 800 grit for one - $30 - 
Concrete Countertop Details
- Includes filling voids with concrete fortifier + concrete, then sealer, then wax, and silicone between slabs to fill in cracks. 
- 22", 12 pad sander - 500-1000 sf/hr rate - . If there are 8 grind steps - that is a whole day job for 500 sf.
- 15 amp - 11" width. 
Densifier and Guard
- Densifier - lithium based - 
- Stain guard - waterproof, probably not breathable - applied before last polishing step - 
- Lithium vs silicate densifier - . Lithium penetrates deeper.
- Sodium silicate densifier - 
- Colloidal silicates appear to be even better? 
When to Densify?
- 200-400 grit step most of the time.  Otherwise it doesn't penetrate enough? Or prevents you from buffing properly on the higher-shine grit?
- If really soft - densify early - so it could be shined at all. 
- How much to add? Until rejection. No controversy on this. Just read the floor. 
- Start with 5000 PSI concrete, not 3500 PSI - it will polish better 
- For longest lasting floor - use potassium silicate, which penetrates more. . For shiniest use lithium.
- Densifier seals cracks up to 0.7 mm 
- Use cementitious filler for cracks 
Guard or No Guard?
- Read more - 
- For residential - no guard.
- Guard wears out. Shine is harder and lasts longer = lower maintenance cost + better look.
- And in all cases - it's a call to opensource it, as the industry is 'segmented' as the article says.
- Throughout the process, a densifier is used to harden the concrete surface, which allows the concrete to be polished. A number of densifiers can be used; these consist of lithium, potassium or sodium silicates. In some cases, a grouting chemical is also used to fill in any holes, cracks or imperfections that were exposed from the initial coarse grinding step. The concrete can be also finished with a natural-look impregnating polish guard, which penetrates 2–5mm inside the pores of the concrete to prevent any deep staining from oils and spills. It is also breathable and not a sealer (as a sealer actually totally seals the concrete and does not allow vapor transmission). -
- If you just grind, no polish - you can use sealer - but then it won't be the natural shine that is obtained from going to finer grit.
- Discovered only in the 90s?
- Use densifier - hardens the concrete
- Use grout if holes are revealed. Grout is typically cement+water+sand, or epoxy of acid and oil is expected.
- Use polish guard - to prevent deep staining from spills
- $3-12/sf