Plaster: Master or Disaster

A big step in finishing the upstairs got started this week.  I mixed my first batch of base-coat plaster and went to work skim-coating the walls of the closet in the Master Bedroom.  This was my first foray into plastering so starting with the closets allows me some training surfaces which will stay out of sight to all but those interested in what's hidden in there.  (What Alberto Gonzales and his minions think of my first attempts at plastering means little to me.)

I must admit, I was nervous about this job.  Plastering is a bit of an art and once it sets up and cures on your wall, there's no getting rid of it without some serious demolition.  So I read all the product literature I could find, and got advice from as many people as I could who had experience working with plaster, and then dove in.

The job really requires two people because as you start working on one wall surface, you can't stop until that surface is finished.  If you start running out of plaster, you need someone else to start mixing another batch while you're applying the current one.  I was able to mix up small batches and apply them myself for finishing the closet walls and in only one instance did I run out.  The half-finished wall set-up while I mixed up another batch.  The result of finishing a single surface with two separate sets is a wall that looks like it's been patched.  In the closet, it's not a problem.  It might not be a problem for an oft-seen wall in an old house, but it would stick out if all the other walls don't share the same characteristic.

I'll be getting some help over the next week or so as I take on the rest of the plastering project, but when I'm working alone, I'll have to make sure I mix up batches that are large enough and not mind wasting what doesn't get used.

The tools needing for applying a base-coat of veneer plaster are:

• Plaster hawk
• Trowels (one large, one small) --get good ones, don't skimp
• Base-coat plaster
• Heavy-duty 1/2" drill with cage style mixer
• 2 clean 5 gallon buckets, one containing a few gallons of cool clean water
• 1 large bucket or tub with water for cleaning smaller buckets and tools
• Table, about 30"x30" covered with plastic for serving up mixed plaster batches
• Rosin paper for covering all the floors.

The process for mixing a small batch goes like this:

1. Cover all your work area floors with rosin paper.  A lot of plaster will hit the floor as you work and it's not easy to clean up.  This is no joke.
2. Add about a quart of cool clean water to the clean dry bucket. (Note the emphasis on clean. Impurities in the mix will affect how the plaster sets.)
3. Start sifting some dry plaster into the water and begin mixing it with the cage mixer.  Keep adding dry plaster and mixing until the mix starts to "peak".  You want the plaster to be a consistency somewhere between yogurt and peanut butter.  You need to be able to move it around with the trowel without a lot of effort but you also want to be able to transfer it from hawk to wall without it sliding off onto the floor.
4. When you think you've got the right consistency, mix it some more to make sure it's all mixed in but don't mix it for more than 5 minutes altogether.  The more you mix it, the faster it'll set and generally speaking, you don't want it to set-up quickly.
5. Dump the batch onto the plastic covered table, getting as much out of the bucket as you can.
6. Clean the bucket and the heavy-duty mixer.  This is where a helper comes in handy.  You need to get the tools and mixing bucket clean before you start mixing another batch, and before the plaster sets up on them.
7. Now to get it on the wall.  Scoop some of the mixture onto your hawk and head to the wall/ceiling.  With some wrist action, use the trowel to pick up plaster from the hawk and slop it onto the wall.  Spread out the plaster, get some more and repeat.  Work from one corner towards the center and if it's a wall, from the top down.  When you get near the floor, be careful not to pick up any dirt. Don't work the material too much, just get it on the wall with a relatively uniform thickness.
8. Once you've got the wall covered, let it start to set up.  Once it has started to set a little, use your trowel to smooth it out, again not working it too much, just one pass if possible.  This is where you'll be glad you spent a little more and got a good trowel.
9. If you're doing more than one wall with a given batch, work on opposite walls, not adjoining ones.  You'll want to finish the adjoining wall after the current one has set up well.

When I get some helpers on the job, I'll be able to take some action photos...

handyman