5 Common Mistakes with Slate
5 Common Mistakes with Slate
Slate is dense and chemical-resistant, but its layered structure and textured finish create unique maintenance challenges. Most mistakes come from treating slate like smooth stone.
Mistake #1
Using wax on outdoor slate
Why this is a problem
Wax makes indoor slate look beautiful, but outdoors it turns white and flaky in rain and freezing temperatures. The wax also makes the surface dangerously slippery when wet.
How to fix it
Strip the wax with Lithofin Wax-Off. Clean thoroughly and let dry before applying an appropriate outdoor treatment.
Prevention
Outdoors, use Lithofin MN Colour Intensifier or MN Stain-Stop instead of wax. These penetrate the stone rather than sitting on top.
Mistake #2
Not filling natural clefts before sealing
Why this is a problem
Slate's natural clefts and fissures trap dirt, food, and moisture. If you seal over these unfilled gaps, the dirt underneath remains trapped and discolours over time.
How to fix it
Strip the sealer, deep-clean the clefts with a stiff brush and Lithofin MN Power-Clean, let dry, then re-seal.
Prevention
Before sealing, thoroughly clean all clefts. Fill deep fissures with a colour-matched grout or filler if needed.
Mistake #3
Scraping off flaking layers
Why this is a problem
Slate naturally separates along its cleavage planes. Picking or scraping at loose flakes pulls off more material than intended, creating an uneven, patchy surface.
How to fix it
Smooth rough edges with fine sandpaper (400 grit). Apply Lithofin MN Colour Intensifier to blend the repair with surrounding stone.
Prevention
If layers are lifting, stabilise them with a penetrating sealer rather than removing them. Minor flaking is normal and adds character.
Mistake #4
Using oil-based products on light-coloured slate
Why this is a problem
Oil enhancers permanently darken light slate. If you wanted a "natural" look, you now have a dark, wet appearance that can never be reversed.
How to fix it
There is no reliable way to lighten oil-darkened slate. Prevention is the only option.
Prevention
Test ANY colour-changing product on a hidden area first. For light slate, use Lithofin MN Stain-Stop (invisible protection) rather than colour enhancers.
Mistake #5
Ignoring rust spots on ferrous slate
Why this is a problem
Some slates contain iron pyrite inclusions. When exposed to water and air, these oxidise and create rust stains that spread outward. Ignoring them lets the stain grow.
How to fix it
Apply Lithofin Rust-Ex directly to the spot. Let it dwell for 15-30 minutes, then rinse. Repeat if needed.
Prevention
Seal ferrous slate immediately after installation. Check for iron inclusions (metallic specks) when purchasing - choose low-iron slate for wet areas.
Need help with Slate?
Use the LithoFinder wizard to find the right product for your slate surface, or read the full Slate care guide.