Sunday, February 19, 2012

On Stripping Coatings From Surfaces

In case you're just tuning in, I'm in paint stripping mode in the parlors. The woodwork is redwood and was originally painted, so the goal is not to get back to bare wood where I can do a clear finish, but rather to get rid of the layers and layers of paint to regain definition in the high Victorian millwork and to get rid of the many drips and runs from past, poorly applied paint jobs.

I have stripped coatings off wood in seven wood intensive rooms in the house. By “wood intensive” I mean all of the rooms either had a wood dado of some type going three to four feet up the walls or, in the case of the stair hall, a highly ornate banister. All of these rooms also had high Victorian fluted casing, plinth blocks, and head blocks. Using flat, unadorned wood was not something Victorian era architects normally did. It looks great, but it is a bitch to strip. The one thing I can say with certainty is there is no one, single, best way to strip coatings off surfaces. Anyone who tells you otherwise simply has not done enough of it. You really need to start by asking five basic questions.

1) What are you stripping the coating off of?
2) What is the coating you are stripping?
3) What was the original surface coated with?
4) What is your goal?
5) What can you devote to the project?

Hopefully question one is an easy answer for you. If you're not sure then there is a good chance you should not be doing the job in the first place. Metal, stone, glass, tile, wood, and brick are all going to be treated differently. In this case, I am dealing with wood. Question two may seem simple, but it is the most tricky, really. If there are multiple layers of coatings, then what is on top may be different than what is on the bottom.

Question three is where the answers really become important and sometimes difficult to determine at first. In the case of stripping off wood, which is what I'm doing now, how I go about the job really depends on whether the original surface was shellac or paint, which were really the two main choices for this area at the time this house was built in 1895. If you are working with more modern construction you could have polyurethanes to deal with.

The answer to question four makes a big difference, too. Do I want to get back to bare wood so I can apply a new clear finish or do I just want to get off layers of old coatings to regain definition. With high Victorian millwork, the beautiful detail often becomes muddied with layers and layers of poorly applied paint jobs.

Question five can refer to both money and time. If you have wads of cash to throw at the project then hire a professional and let them worry about the answers to questions one through four. If you are doing it yourself then time, money and to some extent, comfort come in to play. By comfort I mean that I'm not willing to spend hours and hours for weeks on end in a respirator and gloves in an unheated room on my knees stripping paint.

Money is really determined by what method you chose. A heat gun can be a relatively small investment and can last for years. Even the infrared heat gun can be a good investment when compared to chemical paint strippers. Personally, I don't think the investment in an infrared heat gun is worth it unless you are stripping the siding on your house.

Depending on what the answer is to question three though, the heat gun can be a slow and exhausting process. If the original surface was shellac the coatings come off as if by magic. I have had several layers of paint come off of highly detailed woodwork is sheets when it is hit with a heat gun if the original coating was shellac.

If the original coating was paint then it is a completely different story, in my experience. If it is a flat surface I will still go with the heat gun in most cases. The paint does not come off easily, but it is really just a two step process. Strip with the heat gun in one pass and then sand smooth. Because the surface is flat I can use an electric sander. Sanding is a must when stripping paint off wood because the heat gun can cook any remaining paint and leave a crunchy, uneven surface. Latex, lead, and calcimine paints all react differently to heat, and the level of heat can give you different results. Regardless of all of those factors, the whole process, all be it strenuous at times, goes pretty quickly on flat surfaces.

At least that can be the case when your answer to question four is going to be that you are going to repaint. Even still, that is not a blanket statement that applies to all situations. The answer to question one now comes in to play. In the case of wood, the outcome can depend on whether you are stripping off hardwood or softwood. This can also depend on the answer to question five. If you have a lifetime to spend on the project I'm sure you could strip lead paint off balsa wood and get back to a clean bare surface at some point. Let's face it, art restorers spend dozens and dozens of hours stripping grunge and shellac off paintings. They also use tiny instruments while working under magnification and get paid a few hundred dollars an hour to do the work.

When answering those five questions, at some point you get in to an area that can not be answered with a question on a punch list. That has to do with what is acceptable to you. Even when the original surface was shellac it is sometimes hard to get all of the paint off. With fluted millwork you also run the risk of accidentally rounding off corners when sanding. This gets in to the larger discussion of restoration itself. How far back do you go? When is it good enough? Everybody has their own idea of perfect.

So back to the parlors I'm working on now and the five questions. Here's where I end up.

1) High Victorian redwood millwork. The 2 rooms are roughly 28 X 15 with 5 large windows, one small window, and a 2 part 12-inch high fluted baseboard. The 2 stained glass windows have wood muntins, with the larger window having 41 pieces of glass. There is also fluted casing and detailed window stools. All of the plinth blocks and head blocks must be replaced.
2) I am stripping multiple layers of lead and latex paint. It is really hard to say how many layers there are. I can see 6 or 7 distinct colors, but that could represent twice that many layers, or more.
3) I'm going to say lead paint, but I haven't tested it, and I probably won't. More on lead paint below. I suspect there was a primer layer and then a pigmented layer put down in 1895, and then the rooms were painted 3 to 5 more times with lead paint before several layers of latex paint were applied. The last time the rooms were painted was in 1999 by the previous owners.
4) Getting back to a clean surface where the definition of the millwork is presentable. Some of the latex paint was applied so poorly, the painters really had no respect for their workmanship at all. On top of that, the latex paint chips off the old lead paint very easily, so in areas there are large chips missing from the top coats. The original lead paint is a permanent part of the wood now. As you will see below, even after multiple applications of paint strippers there is no bare wood revealed. I had a similar experience in the butler's pantry, where I used a heat gun.
5) Not as much as I would like is always going to be the answer, but with each passing year of working on the house this becomes even more the case. Simply put, I don't have the time or the stamina to devote to the projects anymore. Eight to ten years ago I probably still would have gone at these rooms with a heat gun because I had more time than money back then. Now, money is still tight, but time is even tighter. It is not even the time that would need to be spent with the heat gun that is the issue. It is the sanding that takes so long. I stripped a lot of the kitchen with a heat gun and I spent more time with sandpaper in my hands that I did with a heat gun. Of course, some could argue I'm overly detail oriented.

I'm going with chemical strippers this time and in the past I would have used a methyl chloride based product. They work quickly because they work through evaporation, but because of this there is a narrow window of time where they must be removed. With methyl chloride based products you also must wear a respirator, chemical gloves, and the vapors are flammable. That is not to say they can't be used safely, and I have many times.

This time I'm trying the high-end stuff. Mainly because I want a longer dwell time. You can think of dwell time as the time it takes the product to do its thing. I don't want to have to rush to take it off, so I want a longer dwell time. With some products you can cover them and let them sit for hours or even days before you take them off. One such product comes with it's own paper to cover it.

In the past I used a product called Peel Away. There are at least two types of Peel Away, and to be honest I don't recall which I used. It worked, but it was not worth the cost. Peel away comes with Peel Away paper that you cover the stripper with to increase the dwell time. I had more stripper than I did paper, so I had to buy more paper. I used this in the kitchen and what ever the original finish was, it liquified and oozed out from under the paper and on to the floor. It was a huge mess, but that may have just been because of the type of paint that was used in the kitchen originally. I have no idea.

Another product in the same category, which I tried once about 8 years ago was Ready-Strip. I had disastrous results with it. It's claim to fame is that it changes color when it is ready to be removed. I didn't keep a close eye on it and by the time I checked back in it had changed color and dried on the surface. It was a nightmare to get off. That was when I purchased my first heat gun.

This time I'm testing two products, Smart Strip and Safest Stripper. The first is made by Dumond, the same company that makes Peel Away, and the second is made by 3M. Both are surprisingly similar. Both are odorless, non-toxic, and non-flammable. They both have the color and consistency of hand cream. The 3M product says you don't even need to wear gloves when using it.

I've tried Safest Stripper with 3 hour, 24 hour, 72 hour, and 1 week dwell times and got about the same results with all four times. For periods longer than 3 hours I covered it with plastic or wax paper. The wax paper worked best. With the Smart Strip I've tried it so far with 3 hours and 24 hour dwell times. With both products I needed two applications, one for the latex and another for the older oil paint. Neither product would take me back to bare wood, but that's not really the goal.

The costs were similar, about $18 a quart, but I got a contractor's discount when I bought the Smart Strip, so all things being equal, if I chose one of these products I would go with the Smart Strip. It is cheaper by the gallon. I think around $55 a gallon. A ballpark guess would be 3 gallons for all of the woodwork in both rooms. There is a professional strength version of the Smart Strip, which I didn't try.

The biggest selling point with these products is the safety when removing lead paint. With a heat gun you are releasing vapors in to the air and with sanding you are releasing lead in to the air. Personally, I think the whole notion of lead paint being a danger is over-stated. As an adult my body can deal with a certain amount of lead. The real danger is to children who are still developing, but again, I think the danger is greatly over-stated. If you have children in the home you can still use a heat gun and do some sanding and if you take the proper precautions I think there is little danger.

So here's where I'm at.

This is the 3M Safest Stripper. This first shot shows two stages of stripping under plastic. On the left is the latex paint. It really bubbles up under the stripper. The old oil paint never really does that, even with the second application.

Here it is after two applications on the right, one application in the middle, and at the far end there has been nothing stripped. At the far end you can see how the latex paint chips off the old oil paint in large chips. There is just no way I can paint over that again and make it look nice.

On the right side of the second photo you can see 3 colors. There is an almost white color (primer or first coat?) in some areas, and very pale yellow and then a darker yellow. These are definitely 3 coats, but they are so thin that I really won't need to sand. This is moments after the stripper was removed and there has been no cleaning or sanding. This is the goal.

On the middle area where you see the green is what is between the yellow layers and the newer latex layers. This looks to be 3 layers of older oil based paint. If I stopped here I would need a lot of sanding to make it smooth. It is hard to tell in the picture, but this is a very uneven surface. Again, not good enough for a new coat of paint.


Sean said...

Looking great! Just a mater of lather rinse repeat for the rest of the room....

purejuice said...

this is an awesome essay on the nature of labor itself, plus really good tips on restoration standards. thank you.