GTC

Have a look at this ebay item number 161054730457.

Might be a cheaper option if you dont need a coloured sealant.

Ben

Thanks Ben. That's very cheap! I'll have a look at the product specs.

I note they say "tinting is available at no extra cost”. I do need tinted paint as the concrete has been quite stained in places by rusty nails and other substances during construction. If it were an open garage that I could hose out I'd probably use acid etch on it first, but I can't hose out this place.

The rear wall of this workshop space is one side of an emergency escape tunnel, the concrete roof of which is 1.2 metres wide by 13 metres long. This slab provides a very useful storage space 2.4 metres above the floor.

Problem is the builders did not clean up that area and it's taken me 2 days to remove debris and white mortar dust in preparation for painting that slab, by vacuuming, wet mopping and sweeping away the dust.

Today I gave it a good coating of Berger Jet Dry paving paint and it's now ready to be used.

I'd forgotten how tiring it is standing on a ladder for hours on end over a 3 day period.

Now that tradies are coming back to work after the break, I'll be chasing quotes to get the floor sanded ahead of using a high quality tinted sealant on it. I'd rather acid etch it myself if I could, but the associated hosing out is not an option.

Well, with quotes of around $2,500 to grind the concrete I'm dumping that idea!

I'll look again at ways of acid etching. Will talk to some experts.

Ouch
Guess I got lucky a couple of years back. Had the concrete on the front verandah, 2m x 6m, ground for $90.

Yesterdays job was 3 hours with a 5 inch grinder taking the shine of the tiles on the steps so I could paint. Its not fun.

There is some sort of 'primer' for concrete & tiles. My paving paint mentioned it on the tin, but none to be seen at the shop.

Acid is the obvious choice, but unusable in your situation

It's around 80 sqm and the tradies say it would take many hours and they would go through at least two cutting heads in the process.

I'm trying to find out how I can etch it without needing to wash the etch away with a 3000psi water jet as recommended.

When the developer's office opens again next week, I'll ask them how the builder created the smooth concrete surface as that may help me determine exactly what I need to do to get the sandpaper-like finish required for sealant to grip.

The delay is starting to bug me as I need the floor done before I can do anything else.

I decided to do a small acid etch test today using diluted hydrochloric and it worked well. Took the sheen off the concrete surface. I mopped up the acid with fresh water containing some ammonia solution, then mopped again with fresh water.

There's plenty of calcium salt lifted in the process, so I'll attack that with Calcium, Lime and Rust remover before washing the result with sugar soap followed by a final rinse.

It's a lot of extra work because I cannot use a pressure washer, but I'll get the job done.

There are cheap wet vacuum cleaners around these days, or one from an op shop. Maybe you could sacrifice one of these to quickly pick up the etchant and neutralising solution.

I do have a 20 litre stainless steel wet & dry vacuum which cost me $78 -- it's what I used for the cement dust on the concrete shelf that I mentioned earlier. But I'm not keen on using it for this job.

I'm happy enough to use the mop and bucket. I need the exercise and I have the time.

And I should mention that I have been advised to use phosphoric acid in lieu of hydrochloric to avoid the collateral corrosion that hydrochloric is infamous for.

Phosphoric acid is also the active ingredient in rust-fixing solutions, so any incidental contact with bare or oxidised metals will be beneficial in forming an anti-corrosive coating.

Maven

Yes, there's the rust conversion aspect to it but it's a hell of a lot more expensive than hydrochloric. Here are the prices for 5 litres:

Hydrochloric: ~ $12
Phosphoric (85%): ~ $160

The 85% stuff is the most commonly available.

If I opt for phosphoric, it seems I won't be able to avoid the cost. I spoke to a chemist at one of the suppliers today and he said that the continuous demand for phosphorous keeps its price high (compared to the other commonly used acids), with fertiliser companies or their subsidiaries owning many of the phosphorous rock mines. Add to the huge agricultural demand for phosphorus the fact that phosphoric acid is used as a cleaning agent in numerous industries -- including dentistry, not to mention rust conversion, etc, it's a very popular product.

So, from an economic standpoint I may have to re-consider hydrochloric and just take lots of precautions.

I'll have a word with an experienced brick cleaner that I know and see what he says.

I'd have to say that at the costs you are now contemplating, I would be looking again at vinyl floor options, rolls or tiles.

It has the additional benefits of being easier on the feet if you are standing around on it, and also more forgiving if you drop anything like a radio valve, glass, mugs etc. Seems to be available new at about $40/sqm at top industrial grade, cheaper at thinner types. Not to mention less work to install.

As a penny-pincher, I would look for much cheaper second-hand vinyl that turns up all the time from other people's refits.

Maven

I did look again at tiles, but painting is far cheaper on the wallet, albeit labour intensive. Once I have the floor sealed I'll probably use rubber or carpet tiles along the run of the bench for the reasons you outline.

I just had a long conversation with a friend who has been in the brick and concrete cleaning business for decades.

He's done plenty of acid etching in his time and gave me lots of tips. He did his own workshop/garage 10 years ago in two-pack and it's still like new.

He suggested that I go ahead and use hydrochloric diluted between 10:1 and 6:1 as necessary and use soda ash (washing soda) in the rinse water as the neutralising agent.

He advised me to be careful not to get acid in the Besser brickwork as it tends to leach out later and cause problems.

As for cleaning up, he has a special vacuum cleaner with rotating spray jets -- sort of like the old Hoover cleaners had rotating brushes -- and said I am welcome to use that if I want. He even offered to send one of his boys over to help if I get into a mess. Nice guy!

So, it looks like I'll take that route, but I'll have to fit a garden style tap to my plumbing. He suggested a temporary arrangement off the cistern supply.

I am still to decide on the paint. There are supporters of both one and two pack systems. Modern solvent-based paints have come a long way since the paving paint of old. For the required two coats I'll need a 20 litre drum of the stuff. One pack is easier to use as there's no decanting, mixing and going off time to deal with. And it's cheaper.

Decision time.

One other consideration with hydrochloric acid is the fumes. Straight hydrochloric acid smells like chuck because it is basically the same acid that is in our stomachs but in a confined space it can burn your windpipe and lungs. Good ventilation is recommended.