How to Mix Thinset Indoors Without Dusting the Whole Room
Open a bag of thinset inside and the room goes grey. Tilers who mix in finished houses have a cheap fix, a free one, and a lab test on one of them.
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The bag of thinset tears open, the first scoop hits the bucket, and a grey cloud climbs out of it. Ten minutes later it's on the windowsill, the towel rail and the inside of your nose. The usual advice is to mix outside.
If you're re-tiling a bathroom in January, or the only way out is through a finished living room, outside isn't on offer. Tilers who work in other people's homes have the same problem, and they've settled on two answers. One is a cheap lid. The other is free.
What do tilers put on the bucket?
A hood that clips onto the rim, with a vacuum hose plugged into it. In r/Tile, a tiler posted it as a friendly public service announcement: a thing that "clips onto a bucket so your vacuum can inhale all your mortar dust".
It's the WaleTale, which tilers on Reddit spell whale tail and the box spells as one word. It hooks over the rim of a five-gallon bucket and takes a shop-vac hose. The vac runs while you mix, and the dust goes sideways into the hose instead of up into the room.
The person who posted it says it makes mixing indoors totally doable, with a gentle hand on the mixer, and another tiler who'd had one for over a year called it awesome.
In a later thread about keeping dust down in clients' homes, one tiler's go-to is a whale tail and a tarp. With those, they can mix inside on most jobs.
These are game changing. Now all thinset and grout is stored and mixed indoors. Temperatures are correct for mixing, even in winter.
u/Raidthefridgeguy, in r/Tile
That tiler's other reason is one you only think of after it happens. No more carrying a full pail of wet thinset through a clean house, and no more having it split on the way.
Did anyone test it?
Yes, a federal safety lab. In December 2017, NIOSH, the US agency that researches workplace health, ran a test at a union training centre in Ohio.
An apprentice bricklayer mixed twelve batches of thinset in a five-gallon bucket. Six with nothing on the bucket, six with the hood and a vacuum.
The air sampler clipped near his collar measured 84% less respirable dust with the hood on. Respirable means the fine fraction small enough to reach deep into the lungs, which is also the part a broom never sees.
Read the figure for what it is. Each batch ran about five minutes, in a training centre, with one experienced mixer.
The runs were too short for the lab to measure silica, the part of cement dust the rules are about, and the report says so plainly. It also says the results shouldn't be compared to an exposure limit. So it's a solid "the hood catches most of the dust", not a safety rating.
What vacuum does it need?
A wet-dry shop vac, and the lab used an ordinary sixteen-gallon one. The maker's recommended airflow is 100 to 150 cubic feet a minute. That's normal shop-vac territory, and both vacuums in the test fell inside it.
The filter is the part to get right. The tiler who called it game changing added a warning: use a HEPA filter, or the vac is just sending the fine dust all over the room.
The lab saw the same thing. Its shop vac had no HEPA filter. The dust readings in the no-hood runs crept up as the session went on, and the report suggests that was the vac blowing fine dust back out. Its advice is that a HEPA vac is probably the one to use for thinset.
Two smaller things from the same report. Push the hood down to the full depth of its slot. The one run where it may not have been seated properly was also the one that caught the least.
The bucket rim also blocks about a fifth of the hood's opening by design, which the lab calls out as room for improvement. The 84% was measured with that in place.
Is the free version as good?
Several tilers get by without the hood. They put the wide flat floor attachment on the shop-vac hose, lay it across the top of the bucket, and pin it down with the bucket handle.
The variations run from the clip-on end of a Ridgid hose, which one tiler reckons works just as well as the whale tail, to a home-made bucket attachment, to a vacuum simply taped to the bucket.
The handle trick has no measurement behind it that we could find. The hood has one short lab test, the handle trick has tilers' word, and both camps mix indoors.
A hose held at the bucket rim is most of the idea. The hood is the version shaped for the job, and it clips on by itself.
What it won't do
- Cutting dust. The hood catches dust at the mixing bucket. A wet saw, a grinder or a dry cutter is a separate problem.
- A dumped bag. The tiler with the tarp puts it well: you "can't just dump the bag or go full send on the mixer". Pour slowly, start the mixer slowly.
- Odd buckets. It's made for a standard five-gallon pail, and the construction research centre CPWR lists it as fitting 3.5- and 1-gallon ones too. A mixing barrel or a square tub is out.
- Come cheap. The tiler who posted it thinks it could be cheaper, and in the same breath says it solves a big problem.
Start with the vac you already own. Put the flat attachment across the bucket, pin it under the handle, and mix one batch with a slow pour. The hood is the step after that: it clips on by itself, and it's the one with a measurement behind it. Either way, the HEPA filter goes in before the first bag opens.