Plaster finishing looks simple when it’s done right, but getting it there is where most people get stuck. The goal is to have a smooth wall that lasts, but small mistakes early can create big issues down the road. Cracks, uneven patches, or flaking often show up when things aren’t done properly. Fixing these issues later is usually harder than getting it right from the beginning.
In Ottawa, where seasonal temperatures swing, poorly finished plaster can lead to bigger problems. That’s why knowing what not to do is just as important as knowing what works. If you want lasting results, avoiding the common mistakes below is a solid place to start.
Skipping Surface Preparation
Plaster won’t bond well to a dirty, greasy, or damaged surface. Even if a wall looks clean, hidden bits of dust or old paint can make the plaster peel or crack later. It might seem tempting to jump ahead, but skipping this stage often leads to extra repairs down the line.
Before you start plastering, the wall needs to be clean, dry, and solid. This means checking for any moisture problems and fixing loose paint, damaged drywall, or soft spots. Many older homes in Ottawa have walls that need some attention before new plaster gets applied.
Here’s a quick checklist for surface prep:
– Clean the surface with a damp sponge or gentle cleaner to remove grease and dust
– Patch holes or cracks with filler and sand them so the surface is level
– Remove any loose paint or debris by scraping or sanding
– Use a bonding agent or primer if the surface is sealed or very smooth
– Allow the wall to dry completely before applying plaster
Skipping these steps weakens the base underneath, and those problems will eventually show through the finished plaster. A bit of prep work early can save hours of rework later.
Incorrect Mixing Of Plaster
Getting plaster to the right consistency is one of the most important parts of the job. If it’s too watery, it slides off the wall. If it’s too thick, spreading it evenly becomes a struggle. Uneven mixes also tend to dry inconsistently, leading to cracks or patches that just don’t look right.
While some people try mixing by feel, sticking to the water-to-plaster ratio on the package is a safer bet. It helps guarantee better results. Always begin by pouring water into a clean bucket, then add the plaster while stirring to prevent lumps. Tools matter here too. A paddle mixer works better than trying to stir by hand, especially on larger batches.
Another overlooked mistake is skipping the second mix. After the plaster sits for a few minutes (a process known as slaking), it needs to be stirred again. Not doing this can leave you with rough, uneven texture that’s hard to cover later.
One Ottawa homeowner tried plastering a small wall in their bedroom and didn’t mix the batch well. The result was uneven texture, dried lumps, and tough sanding. In the end, they had to chip it away and do the whole section over.
Stick to clean tools, proper timing, and accurate measures. It helps all around, from smooth application to better durability.
Applying Plaster Too Thickly
It might seem easier or faster to put one thick coat over a damaged wall, but that usually causes more problems than it solves. Thick plaster often dries unevenly, leading to sagging or cracks. Even if it looks decent at first, it may shrink while drying, making flaws show up days later.
For a better result, go with multiple thin coats. Work in layers and let each one dry before the next gets added. This lets each layer cure properly and gives a more even finish.
Tips for applying smoother coats:
1. Use two or three thin layers instead of piling on one thick coat
2. The first coat sets the base and fills any dents or holes
3. The middle coat smooths things out further
4. The final skim coat gives the polished look before sanding
This method takes more time, but it’s easier to manage and correct. When autumn arrives in Ottawa, and indoor temperatures fluctuate, thick plaster can stay damp longer and may not dry evenly. Thin coats deal better with the shifting climate and protect against peeling walls.
Ignoring Drying Times
Speeding up the job may seem like a good idea, but not letting each coat dry fully is one of the biggest mistakes in plaster work. Plaster needs time to cure between layers. If you move on too soon, it can trap moisture or lead to weak bonds between coats.
Drying isn’t just about time on the clock. It depends on airflow, humidity, and temperature. Ottawa has long winters, which means central heating and dry indoor air. Trying to force drying with heaters or fans can throw off the process. Instead of drying evenly, the surface crusts over while moisture stays locked inside.
Here’s how to let plaster dry the right way:
– Wait at least 12 to 24 hours before adding the next coat, depending on layer thickness
– Avoid using fans or cranking the heat to speed up curing
– Aim to keep the room at a mild, steady temperature
– If a section feels cool or looks darker, it’s probably not dry yet
We once saw a room in Ottawa where freshly applied plaster was painted too soon. In a few days, the paint bubbled, and ridges showed through. The plaster underneath was still damp, and it had to be scraped and repaired. A bit of patience at this stage could have kept everything intact.
Drying time makes all the difference. Rushing through it can double the work, especially if you’re hoping for a clean look the first time around.
Common Finishing Mistakes That Ruin The Look
Finishing is often where things unravel, even if all the earlier steps went smoothly. From sanding too hard to missing spots, this part needs finesse. Rushing the final steps often leads to a wall that looks okay from one angle, but terrible from another.
Over-sanding creates gouges and scratches in the surface that don’t disappear under paint. It might be tempting to sand aggressively to fix a couple of bumps, but that approach usually backfires. On the flip side, under-smoothing leaves lines or edge marks that become obvious once the wall catches the light.
Some tips for a cleaner finish:
– Use a stainless steel trowel for smoother passes and less drag
– Start smoothing once the plaster firms up but is still slightly damp
– Clean tools often to avoid hardened bits scratching the surface
– Blend edges instead of leaving sharp lines between passes
– Check for missed spots under both natural and artificial light
The key here is balance. Don’t push too hard, and don’t rush to the finish line. A few missed sections or rough areas can stick out badly once paint goes on. Taking an extra few minutes to smooth things properly beats spending hours sanding down rough patches afterwards.
Ottawa homes, especially older ones, often have quirky walls. Crooked frames or uneven patches aren’t unusual. Finishing with care makes sure past repairs blend in instead of sticking out.
Getting It Right in Your Ottawa Home
Plaster finishing doesn’t have to be difficult, but it does take attention to detail. Skipping steps or hurrying through the process creates little trouble spots that turn into big repairs later. From surface prep to finishing, small missteps stack up fast.
Each home in Ottawa can throw different challenges your way. Whether it’s temperature swings, poor previous work, or odd wall angles, getting a clean finish means working with the space instead of fighting it. Patience, proper materials, and solid technique all play a part in success.
Perfect plaster doesn’t just happen during the last pass with the trowel. It begins with a clean surface, continues with a proper mix and timed layers, and ends with care in the finishing stage. Paying attention throughout the whole process gives you walls that stay smooth and last longer.
If you’re hoping to skip the stress and get walls that look smooth and stay strong, let Picasso Paints take care of the work for you. Our team brings years of hands-on experience to every job, ensuring your space gets the attention it deserves. To see how we can help with expert plaster finishing in your Ottawa home, reach out today.