May 26, 2004

In This Issue of The Acid Staining Newsletter

To Redo or Not to Redo, That is the Question

To Redo or Not to Redo, That is the Question

If you are a reliable subcontractor and your stained floors are consistently attractive, you will begin to get frequent calls to redo floors which have been badly finished by other subs. You would be wise to inspect these jobs carefully and weigh the alternatives before agreeing to tackle them. I am sure you have seen the humorous sign which often hangs in auto repair shops:

If we do the work, our price is $50 an hour for labor.
If you watch and make comments, the price is $75 an hour.
If you have already tried to do the repair yourself, the price is $100 an an hour.

I used to be quite flattered when people called upon me to consult on jobs done by other stainers, and would soon agree that, yes, we could do a better job. Now, my attitude is more like that of the repair shop owners.

Be aware that due to the number of unknown products involved, refinishing can be a nightmare. The owner might think that the floors have been acid-stained, but you may discover later that an oil-based, diluted paint has been used - something very difficult to remove and oily enough to throw off the stain when you try to apply it. I interrogate the owner as to what they saw the stain worker do, and ask to see any bottles of product which the artisan might have left behind.

You will have to play detective. In the first place, it is important to find out what kind of sealer was used over the stain. If it was a water-based acrylic, then it can be removed using a janitorial wax stripper (dilute it less than the instructions say for wax removal and scrub with a rotary buffer and a black pad). This is not a quick job. It might take as many as three stripping sessions over the whole floor to get all the sealer off. How many corners and small spaces are there relative to the size of the entire floor? Remember that all corners and edges where the power buffer cannot reach will have to be stripped by hand.

The sealer stripping process will probably remove most of the acid stain color. If it does not, you may be dealing with another product. There are now several brands of imitation acid stain on the market which boast that they are water-based acrylics that look and act "just like acid stains," only they are easier to clean up and nontoxic. This would be fine, if it were true. All the water-based stain jobs I have seen look more opaque and bland than true acid stains. The natural color variation of the concrete beneath does not show through, which gives the surface a flat, dead look.

When we had to remove an acrylic paint stain, we found that by throwing a handful of (children's sandbox) sand under the buffer while we were scrubbing with the wax stripper, we could get enough abrasion beneath the pad to remove both sealer and acrylic stain at the same time. Afterwards, however, we spent extra hours vacuuming sand out of every saw cut and corner of the slab!

Before you bid on any redo, you might need to spend half a day stripping an 8' x 8' section to see if it can be restained to the client's satisfaction. If a penetrating solvent-based acrylic sealer has been used, there is no simple way to remove it chemically. You would need to ascertain which solvent was a component of the sealer, and then apply a "poultice" of thin fabric mesh soaked in the solvent, leave it on for a while, then peel it up and dispose of it. The usual solvents--xylene, lacquer thinner, and naphtha are all extremely toxic to your workers, a fire hazard, and hard on the environment if not disposed of properly. It is best not even to contemplate the chemical removal of solvent-based acrylic sealers.

The only alternative with a really durable sealer is to remove it by abrasive methods. If the sealer layer is old and thin, a power sander might be used. But several layers of new sealer and wax will rapidly clog up the sandpaper's surface, costing you a lot of time and a fortune in paper. Friction from the sander can also melt some sealers and send them even further into the pores of the concrete!

Sand-blasting creates a huge mess in a finished building where people are living or working, so the client will usually reject sand-blasting.

Shot-blasting with steel shot creates less dust, but it also removes the smooth "cream" layer at the top of the concrete, giving a lightly pitted texture to the floor which looks "sugary" once it has been stained and sealed. The photos here are of floors which were shot blasted to remove old black mastic (used to hold down vinyl composition tile). Where the light reflects off the sealer you can see the "sugary" quality and also some speckles where the cleaning process revealed the aggregate in the concrete. We stained a brown border near the walls with the center of the floor in Scofield's Weathered Bronze.

If the entire floor is cleaned in the same manner, I do not feel that the increased roughness is a problem. It would depend on the location of the floors. These are in an office. In a restaurant, cleaning might become more difficult.
I had a client refuse to pay me the last one-third he owed us, because he swore that neither the shot-blaster nor I had warned him that the slab would have swirl marks from the grinder. (We both had done so, but not in writing!) A shot-blasting machine can reach no closer than eight inches from the wall, so a hand grinder must be used in the border areas. Skilled workers will then grind down the small peaks on the surface of the entire shot-blasted floor to make it blend with the border areas, but to a perfectionist (or to someone looking for an excuse not to pay you) this will not be satisfactory.

The clear sealers we usually apply over a stained floor are not thick enough to fill in and level out the pitted texture of a shot-blasted slab. However, there is now a 2-part clear acrylic epoxy on the market which can create a deep glossy surface on such a floor. Epoxies are a good deal more expensive than your other sealers and might need to be combined with a 2-part acrylic urethane over the top to be more scratch-resistant and UV light-resistant.

We have been pleased with the results of Dayton Superior's water-based acrylic epoxy. We use their J-36 and J-39. Call (1-866-329-8724) or go to If you use an epoxy system, you must call the technical representative of the manufacturer to be sure that it is NOT an impermeable sealer. Unless the slab you are refinishing is over five or ten years old, a good deal of moisture will still need to escape from the slab through the sealer, as the slab continues to cure. Having a sealer which "breathes" is still an important part of the system.

Once you have determined the techniques you will need to employ in a redo, and how much more than your usual price you will need to bid, there is still an important intangible to consider: how angry is your client with the artisan who messed up the floors in the first place? Is this anger likely to be transferred to you? By the time you have explained your process to the owner and spent half a day experimenting with your procedure, you will have a pretty good feeling about the character and personality of your prospective client. If this feeling is negative, do not ignore your instincts. You are accepting a difficult job. You deserve a client who will treat you with understanding and gratitude, not irate perfectionism.

In my next newsletter I will tell you about the amazing dustless grinding machine we just bought from the Hilti Company, and of further adventures in the world of redos.


One of the biggest problems we face in the acid staining business these days is trying to keep up with technology. New stains, sealers, tools, and more are being developed all the time, and it's difficult to know what's good...and what will just lead to more headaches.

I've been doing my research and I want to share what I have found. Moreover, I want to make it available to anyone who is interested, and I'm not going to charge a penny!

On the evening of Wednesday, May 26th (8pm Eastern - 5pm Pacific), I'm going to hold a phone-in Q&A session. The call will last one hour, and anyone can join. There will be no charge for participating, all you pay for is your phone call. This will be a normal phone call, most likely long distance but no 900 number or anything like that.

Furthermore, the people on the call will get to decide what we cover. I already have a few topics that I know you'll want to hear about, but the rest is up to you. I'll give you the details on how to ask your questions when you register for the call. Go to the webpage below to sign up now.

There are only 150 phone lines available for this call, so it will be first come, first serve. You snooze, you lose.

If you are in the decorative concrete business, it is especially important that you participate. I will be covering some topics specifically for pros, so be sure to make time for this opportunity!

If you are a property owner or do-it-yourselfer, this will be a rare chance for you to get some real "insider secrets" from the industry. The same deal applies for you, if you are one of the first 150 callers then you can participate at no charge.

I expect this call to fill up, so don't delay. Register on the webpage below today.

If you are have that evening committed and just can't make, I'm going to try to have the call taped. Write to me at and we'll see if maybe there is a way to get some transcripts to you.


As you may know, I've now held four acid staining seminars here in Albuquerque and each one has been better than the last! This summer I'm going to try something a little different, so that everyone who attends gets EXACTLY the training that they need.

Rather than trying to pack everything into 3 intense days of acid staining, I'm going to break the seminar up into two parts, the Fundamentals and the Advanced Artistic Techniques. These 2-day seminars will be held back-to-back, and there is a significant discount for anyone who would like to attend all four days. Furthermore, I am offering an additional early bird discount for anyone who signs up at least 2 weeks in advance.

This is the last time I will offer this course for several months at least, so if you are interested in attending don't put it off.

Space is already filling up fast (especially for the Fundamentals portion). Go to the webpage below for more information on seminar content and registration details.

If you prefer we can email or fax the information to you as well. Write to and we'll get back to you promptly. Or call my publisher Bridgeworks at 1-888-514-1400 and they'll be happy to answer your questions.

I look forward to talking with you tonight, and hope to see you at my seminar next month.

Happy Staining!


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