I've seen at least one paint can label that explicity said NOT to use
TSP. I'm quite sure of this, because it caught my attention. I didn't
get the impression it was an environmental issue, but rather a product
But I've looked at so many paint can labels lately I don't remember the
brand or product name. If I come across it again I'll make a note next
Just a guess,
Many people don't want to use TSP, and don't use it correctly. So
were ever you don't have to, I guess paint manufactures are willing to
brag you shouldn't.
Just a guess, and TSP prep-hater. ;)
tom @ www.FreelancingProjects.com
I long time ago, I learned about TSP's amazing powers. We would steal
some off out ELT's to clean bilges. We had to add very little
relative to the amount of water.
Well, because I know of TSP's powers, I tend to rinse extra hard.
Causing me to wipe down walls over and over, since the littlest amount
of TSP could interfere with paint adheasion.
So, I preferer not to use TSP, and use better paint, or sand down the
surfaces to give the paint bite, and remove dirt.
tom @ www.WorkAtHomePlans.com
Some states (in the US) prohibit the sale of TSP due to environmental
concerns. TSP is a very strong detergent and it is particularly
effective in washing walls and outdoor things (furniture, siding,
decks, etc.). in general wood should not be "washed" with a
water-based detergent. It makes the fibers swell, and then when it
dries you have a rough surface that needs sanding.
Shouldn't unpainted wood be washed before painting? How else are you
going to remove the dust and dirt?
Every paint can label I've read says you should wash the wood to remove
dirt and dust.
Some say even clean new wood must be washed to remove mill glaze.
But what to use? I've heard TSP will interfere with paint adhesion if
not thoroughly rinsed off. But if the wood absorbs the TSP solution,
how can you thoroughly rinse it off?
In such a case, would it be best to thoroughly soak the wood first with
clear water, and only then apply the TSP (or other detergent solution)?
Are there any chemical rinses which could be used AFTER washing to help
rinse away or neutralize any remaining detergent, so it doesn't
interfere with paint adhesion? What about oxalic acid for example?
Many I'm ruled by my parinoia's :)
I don't like washing wood, with water, but cleaning wood with items
like vacuuming and tack clothes. Water can cause the grains to lift
up uneven, and give the wood a 'bumpy' feeling. Also, not liking to
use TSP, I have a hard time thinking I could remove 100% of TSP used
on bare wood.
So I try to sand, vacuum, and tack cloth where needed.
tom @ www.FindMeShelter.com
I presume you are talking about a house or wood
construction outside. In cabinetry and furniture
construction and new interior construction, there
is no need to wash new wood. Woodworkers don't
wash wood, or if they do they sand afterwards.
Water on raw wood has undesirable effect including
raising the grain and warping. If it is old
construction is should have been painted or some
type of finish applied, As a result, washing
doesn't affect the wood (except in small spots
where the paint has worn or flaked off, and those
places should be scraped or sanded).
If there is grease on old wood, you might want to
consider replacing the wood, but if you wash it,
you need to let it dry thoroughly and then sand.
If you have little spots that need washing, just
wash those spots.
To be more definitive, we need to know what you
are talking about washing. In general, dirt or
dust is removed by wiping with a damp cloth.
Washing wood to get rid of mill glaze is just
plain stupid. The only reason to get rid of the
glaze is to improve adhesion and you do that by
lightly sanding with 220-400 grit paper for painting.
Yes you can neutralize TSP if you want. TSP is a
base, that is why it is slippery (slippery is
caused by dissolving the oils and your skin). So
to neutralize it your guess about using an acid is
correct. But, just use vinegar not oxalic acid.
Be careful what you read on the instructions of
paint cans. The manufacture has reasons for what
he puts on the can (mostly for adhesion purposes),
but may not care about some things that are
important to you. A good book on painting and
other finishes is far more likely to provide
useful information. For example, a good
undercoat can be slapped on just about anything
including your hands and it will stick. But you
don't want to put it on globs of mud or something
that will show through.
It's an 8-year-old exterior wrap-around porch with white cedar decking
and stairs, previously oil-primed and latex-topcoated.
There's a 200 square foot section (including stairs) that's in bad
shape. Large areas (as big as a postcard in some cases, or bigger) are
blistering (both paint and primer) revealing large patches of weathered
wood beneath (light grayish-brown).
I don't mind paying top-dollar for a quality paint if I just knew what
to buy and how to prepare the surface properly.
Sanding is out of the question; I don't want the mess, or the dust in
I was leaning toward power-washing, but you (and others) have said
don't wash bare wood, is that correct? (Or is this situation an
What options does that leave? Scraping? I could do that, but how
effective would it be? (Should I use a heat gun or just try to get the
stuff that comes off easily with just mechanical scraping?). And how do
I get rid of the ground-in dirt, if I don't wash it? In your previous
post, you mentioned wiping with a damp cloth; does that advice apply
to the situation I described?
If I wash it, should I use just clear water, or TSP, or TSP substitute,
or something else? If I use TSP, should I use an acid rinse to get rid
of the residue?
Lots of questions I know, but that's what I'm trying to figure out.
I don't mind touching it up every spring. What I don't want is large
areas of blistering that leave the wood unprotected.
Do you have a favorite book in mind which you have found to be
well-written and accurate, that you could recommend?
If you wash the wood with water, it will raise the grain as it dries. I
think that would make the paint stick *better*.
You'd only need to sand it after washing (and then go over with tack
cloth) if you were gonna varnish it and try to get a fine finish.
Yes, porches and decks tend to be an exception
since they are often heavily weathered and a fair
degree of roughness should not be a problem. And
I presume the really dirty areas are the deck. If
I were you, I would get a regular scraper with a
3" wide blade and scrape any loose or blistered
areas, hand wash any really dirty areas with any
good detergent, then power washing with TSP, then
powerwash with clear water, which will probably
lift more areas of paint. Let dry thoroughly and
scrape the edges of any paint to bare wood to
feather the edge.
Make sure that you powerwash solid wood, not
manufactured stuff or plywood.
Since you already have everything painted you
probably have no option but to repaint, i.e, an
oil stain on the deck would not be an option
unless all paint were removed. So, when the wood
is thoroughly dry put on a good undercoat, then
paint with a product designated for porches and
decks. Personally, I would use oil paint and top
coat with two layers of paint. BTW, I don't know
where you live, but a porch in most areas should
not have that much paint damage in just 8 years.
I don't have a favorite book on just painting,
probably any book at Lowes or Home Depot would be
For exterior wood. Dissolve 1/2 c. TSP in 1 gallon warm water, add 1
cup household bleach, add to a garden sprayer. Use a brush with a
long handle, rubber gloves, boots, old clothes, eye protection, and
garden hose. Wash one section at a time. Rinse twice using a nozzle
set to a fan spray. If the deck is really dirty, you may need to wash
it twice. A pressure-washer will work too, although you can damage
the wood. Allow the wood to completely dry before you paint or
stain--perhaps a week. Repair any damaged areas, set nail heads, etc.
You can use "JoMax" instead of the TSP.
Why do all the paint can labels tell you to wash the wood, and many
explicitly tell you to use TSP (which is obviously water-based) ?
If you don't wash the wood, how are you supposed to remove the dust and
dirt and grease and wax (old wood) or mill glaze (clean new wood)?
Trying to be environmentally correct is one
reason. Also TSP is supposed to be more difficult
to wash off than the silicate washing products and
if you don't wash thoroughly, the paint adherence
is adversely affected. Not my experience, but
maybe I use a lot less TSP than some people.
BTW, you should look for "trisodium phosphate", not "TSP". Some
unscrupulous company is selling... I think it's sodium carbonate; under
then brand name "TSP".
Read the label. The fine print will tell you what's in there.
I think you're talking about "TSP substitute". I don't think TSP
substitute is sodium carbonate (washing soda). I think it's sodium
metasilicate. Big difference.
It is my understanding that sodium metasilicate is a slightly less
effective cleaner, BUT it rinses off more easily leaving no residue to
interfere with paint adhesion. Can anyone confirm/refute this?
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