If the gloss coatings in your home have lost their sheen, gone yellow, or are simply looking old and tired, you might be thinking about painting gloss over gloss. But can you paint gloss over gloss? And what preparations must you take to ensure the job is done properly?
With over 20 years of decorating experience, I’ve tackled all sorts of jobs, and painting over gloss with gloss is something I come across often. With that in mind, I’ve decided to put together a little guide explaining the process I use to paint gloss over gloss and also some common issues you might encounter if you don’t do it properly.
Can You Paint Gloss Over Gloss?
You can paint gloss over gloss, however, you will need to follow a particular process and thoroughly prepare the surface before applying the new coating. If you don’t follow a thorough preparation process, the new coat of gloss paint will struggle to adhere to the previous coating, especially if it has retained the majority of its sheen.
Can You Gloss Over Old Gloss?
Paint gloss over old gloss is a slightly easier process than painting over new-ish gloss as the lack of sheen means the new coating has a better key to adhere to.
With that being said, it’s still advisable to follow the same preparation process as you would if you were painting over newer gloss.
What About Water-Based Gloss Over Oil-Based Gloss?
Applying water-based gloss over oil-based gloss is even trickier. Water-based gloss will have great difficulty adhering to oil-based gloss so if you’re looking to make the switch to the more environmentally friendly and yellowing-proof water-based version, I would advise removing the current gloss paint entirely from the surface.
Of course, you can attempt to apply a primer such as Johnstone’s Aqua Guard Undercoat first before applying water-based gloss, however, durability cannot be guaranteed.
How to Paint Over Gloss (and Avoid Issues)
Having applied gloss over gloss countless times over the years, there is one tried and tested method I typically use.
Step 1: Degrease the surface
Use a degreasing product to degrease the surface. Gloss is typically used as a highly effective protective coating and can easily become contaminated in high-traffic areas. Therefore, it’s essential to remove all grease as residual grease can cause paint defects when the new coating is applied.
Step 2: Remove the sheen from the old gloss with wet and dry sandpaper
Get yourself some wet and dry sandpaper and start abrading the old gloss surface until you’ve removed the sheen. This is typically done manually and can take quite a bit of time so I would recommend wrapping the wet and dry sandpaper around a block or something similar to protect your hands and make it easier to rub down.
Step 3: Dust down
Once the sheen is removed you’re going to be left with plenty of dust. It’s important you give the surface a good dusting down as loose dust on surfaces can impact the adherence of the new coating. If you don’t dust down, you could end up with issues such as flaking paint.
Step 4: Apply an undercoat (optional)
There is a bit of an obsession in the decorating industry with using undercoats before applying gloss over gloss however, I don’t believe it’s strictly necessary except in cases where the old gloss has yellowed.
Of course, if you feel more comfortable using an undercoat before applying the new coating then go ahead.
Step 5: Apply the first coat
If you used an undercoat then wait until it has dried and then proceed to apply your first coat. I would advise using a short hair mohair roller for applying the gloss. Natural mohair rollers are fairly expensive so if you’re not going to use the roller for any other projects, it’s worth going with a cheaper synthetic version.
Step 6: Apply a second coat (optional)
Usually, one coat of gloss is sufficient if painting over an old coat but it’s of course worth waiting to see if you’ve achieved the perfect finish. If the opacity after the first coat isn’t great, you can simply apply a second coat after the first coat dries.
How Much Do You Have to Sand Over Gloss Before Painting?
If you’re preparing to paint over old gloss then you will need to sand over it until it has completely lost its sheen. This is typically done using a fine 120-grit sandpaper. Depending on the condition of the old coating, you might want to have a piece of 80-grit sandpaper handy for taking off any previous drips or lumps.
What Happens if you Paint Over Gloss Without Sanding?
Painting over gloss without sanding first is a bad idea. A glossy surface is incredibly smooth and therefore offers no key with which a new coat can adhere to. With lack of adhesion comes peeling and your time and money will be wasted.
Painting Gloss Without Sanding
Even though I’ve advocated for sanding gloss down before painting, sanding isn’t strictly necessary if you use a deglosser or high-quality primer first.
I know of decorators who will use ESP primer, which is designed to bond paint to shiny surfaces, before painting over gloss. You could also use Zinsser 123 which is low odour, quick drying, and more importantly, bonds paint to glossy surfaces.
With that being said, this system is prone to failing on occasion so I stick to sanding!
Final Thoughts
With plenty of preparation, including a thorough sanding to remove the sheen from the previous gloss coating, painting gloss over gloss is certainly possible.
If you’ve made it this far then hopefully you’ve now got the knowledge and confidence to get the job done. Good luck!