Preparing a concrete surface typically involves several key steps:

• Cleaning: Remove dirt, grease, oil, and other contaminants using a concrete cleaner or degreaser.
• Repairing: Fill any cracks, holes, or imperfections with a concrete patching compound to create a smooth surface.
• Etching: Use a concrete etcher to roughen smooth surfaces, enhancing the adhesion of stains and sealers.
• Priming: Apply a primer to ensure a strong bond between the concrete and the topcoat. This step is especially important for sealing and painting projects.

Choosing between waterborne and solvent-based etchers depends on several factors:

• Environment: Waterborne etchers are more environmentally friendly and produce less odor, making them suitable for indoor use. Solvent-based etchers, while more effective at penetrating and etching tough surfaces, emit stronger fumes and require good ventilation.
• Surface Condition: For lightly soiled or less dense concrete, waterborne etchers are effective. For heavily soiled, dense, or previously coated concrete, solvent-based etchers provide deeper penetration and more thorough etching.

It is generally not recommended to apply new concrete coatings directly over old paint or sealers. The existing coatings can interfere with the adhesion of the new product, leading to peeling and flaking. It's important to remove any old coatings through stripping, grinding, or etching to ensure the new coating adheres properly and provides a durable finish.

Repairing cracks and holes involves the following steps:

• Cleaning: Clear out any loose debris, dirt, or dust from the cracks and holes.
• Filling: Use a concrete patching compound or crack filler to fill the damaged areas. Apply the compound with a trowel, ensuring it penetrates deep into the cracks and holes.
• Smoothing: Smooth the surface with a trowel and allow the patching compound to dry according to the manufacturer’s instructions.
• Sanding: Sand the patched areas to ensure a smooth, even surface that is ready for staining, sealing, or painting.

The type of primer you should use depends on the specific requirements of your project:

• Bonding Primer: Ideal for enhancing the adhesion of topcoats on smooth or previously coated concrete surfaces. It helps in creating a strong bond between the concrete and the finish.
• Moisture-Blocking Primer: Suitable for areas prone to moisture, such as basements and exterior concrete. It prevents moisture from seeping through the concrete and affecting the adhesion and durability of the finish.
• Stain-Blocking Primer: Used for concrete surfaces with existing stains or discolorations. It prevents these stains from bleeding through and affecting the appearance of the new finish.