Get plastered!

What to do when you've gotten yourself into a hole

(Second in a series about plaster walls. Last week’s column was about the proper way to hang something on a plaster wall; today’s deals with how to patch a hole, in case hanging something on the wall didn’t go so well.)

The first thing to do is be pleased you’re working with plaster. Fixing a hole in a plaster wall is a bit more art than science, but very doable. The worst parts of the job are setup and cleanup (due to the dust, but one of the products we’ll mention is dustless).

Getting started
First, measure the hole. Your goal is to put something in the hole that plaster will stick to, and it’s called hardware cloth. Think of chicken wire with much smaller holes – the hardware cloth you’ll want to use has a quarter-inch mesh. Cut a piece of the cloth and make sure it’s larger than the hole you poked in the wall.

“Tie a string to the middle of it,” says Mike Frentz, “and then force the hardware cloth into the hole. Then, gently pull on the string until the hardware cloth is flush up against the wall.”

(We’re going to mention three different patch products to fill the hole. Whichever one you decide to use, here’s how to make that hardware cloth stick to the inner wall: coat the edges of the cloth with the patch product before you force it into the hole. That way, when you pull the string, the edges will come into contact with the inside of the wall, and stick. Drying time is important – it can take several hours, but don’t rush it or you’ll be pushing a patching compound right through the hole.)

“Cut the string when dry and then you’re ready to apply your first coat of whichever product you’re going to use,” Mike says. “You’re not going to want to try to fill the hole in one step. First, apply a thin layer of the patching product, enough to cover the hardware cloth and bring you almost level with the wall.” Let it dry.

Your second coat is the finishing coat, and will be raised slightly raised over the hole, making sure all the edges are well covered. Slightly raised means just that – don’t worry about piling patching compound on to the point where it stands out an inch from the wall, because you’ll just have to sand it off.

Patching products
Mike recommends one of five products to patch a hole in a plaster wall. Each has its own set of advantages and disadvantages:

ONETIME, from Red Devil, is Mike’s favorite. It’s a premixed compound ready to use.

Very light weight (that’s important – heavier compounds tend to roll out of the hole and with those, it can be like trying to patch a hole with bread dough. “Most people pick up the container (of ONETIME and wonder if there’s anything in it, it’s so light,” Mike says.

“You can smooth it with a putty knife and let it dry with absolutely no sanding,” Mike says, adding that once customers have tried this mix, they wonder why they didn’t use if before.

(A word on sanding: If you feel confident about what you’re doing, you can wet sand, which is what the pros do, to avoid the dusty mess you’ll get when the patch is dry. Mike hasn’t dry sanded plaster in years. Here’s how: “Wait 15 minutes after applying the second coat and then, with a damp sponge, gently go over the surface, squeezing the excess out of the sponge into a bucket of water. I do it all the time and it eliminates worrying about drying time and cleanup.” You don’t have to do this with ONETIME.

Mike notes ONETIME is the most expensive of the five patching compounds he recommends, starting at a little more than $4 a pint. It also doesn’t dry to an absolute concrete hardness – “you can take your fingernail and draw a line in it when it’s dry,” Mike says. What does this mean? Mike says ONETIME probably is best for small-to-medium size holes. “It’s more expensive, but it lasts forever,” Mike adds.

Ready Patch, also premixed, is the stuff you would expect Mike to hand you if you asked for a can of spackle.

It is less expensive than ONETIME and if you’re a person more comfortable using traditional preparations, this is it. When it’s dry, it’s like concrete (Mike recommends 12 hours drying time per application for any of these patching products.) Ready Patch is the stuff to use for slightly larger holes, something bowling ball sized, for example, because it will dry to such a hard finish.

This is your chance to try wet sanding; if you don’t, you will be sanding down Ready Patch with traditional sandpaper (traditional patch, traditional follow-up) and you’ll wonder how so much dust can be produced by such a small project. Also, this is the stuff that’s like bread dough. It’s tough to keep it from rolling out of the hole.

(Here’s how: Mike says once the first, thin coat is applied and has dried, scratch and lightly dampen that surface – that will help the second, heavier coat adhere.)

The Original Patching Plaster, which is not premixed. It comes in a 4.4-pound box that, when mixed with water, will yield about a half gallon of patching compound.

If you are an impatient person trying to learn patience, this is the stuff for you, Grasshopper, because just getting the consistency right is quite the art. “Most places probably don’t even carry this stuff any more, which is one of the reasons we do,” Mike says. Very, very economical, if that’s an important consideration – this is the least expensive option.

Mike says he rarely recommends Patching Plaster because over the years, superior products like the others mentioned here have been developed and they do the same job, better, with less fuss. There’s a lot of set-up time involved with Patching Plaster compared to opening a can of Ready Patch and starting to work. Also, it has the same problems as any heavier, moist patch – the bread dough effect.

Joint compound. Let’s get something straight. Joint compound was not made to fill holes in plaster walls. It is a premixed preparation designed to seam joints on dry wall. Joint compound is the cheater’s delight and is often used to fill holes in plaster walls.

Very inexpensive at about $5 per gallon. This is the stuff to use for really, really big holes. “I’ve had instances where people have put a thin coating on an entire wall to fix water damage,” Mike says. It does dry to a hard surface, it can be wet or dry sanded.

It just wasn’t made for this job. Drywall is an entirely different animal than plaster walls, and if you don’t do it just right, you’ll always be able to tell exactly where the patch is – unless you’re a professional who does this for a living, in which case that isn’t true. “I kind of size people up when they come in,” Mike says. “If some guy’s got dry plaster spots all over his clothing, then he probably knows how to use this stuff. But if you’ve never done this before, one of the other products probably is the smarter way to go.”

DryDex, a brand new product from DAP called . “It’s only been out a month or so,” Mike says. It’s a premix and weighs in, literally, somewhere between the ONETIME and the Ready Patch.

It’s not always easy to know when your patch is dry. The surface might be dry to the touch, you might start sanding and hit a wet spot, which can be irritating. That’s why DAP made DryDex. It comes out of the tub and goes on pink, and we mean a hot, vibrating, livid, horror movie, better-not-have-a-hangover-and-pry-the-lid-off –this-stuff pink. All of the other compounds we’ve mentioned go on white. However, you don’t have to wonder if DryDex is dry. It turns white when it is.

Too early to tell, but probably not too many. DAP is a quality producer that’s been around for years. And really, it doesn’t matter what color it is – you’re going to paint over it anyway, right?