How much Penetrol (or the like)?

[Jeff Kelety]

Hi all -

Well each coat on the topsides gets better. But only got time for one more. Have thinnned paint to get good even coverage, but still have more brush lines than ought to be.

How much Penetrol do you all use, as in percentage of paint?

I'm using boiled linseed oil in place of Penetrol, but it servers the same purpose, I believe. I'm thinking I need to use more than I've been which is something like a capful per cup of paint. What is every one elses experience here?

Thanks,
jgk

[Matt Middleton]

Hey Jeff
My lesson learned this weekend is to not be afraid of using the Penetrol. When my wife and I first started painting, I was putting only small amount into the paint, and it actaully made it perform worse than straight paint. It wasn't until I read a post here, where someone mentioned going as high as 30-40% Penetrol, that I went back and tried it again with the Penetrol. When I put in the larger amount (maybe 25-30%), it went on without dragging and all brush lines eventually disappeared. My wife laid the paint(Kirby's) on with a synthestic brush, and I tipped with a foam brush.
It worked great for our particular paint and climate, but the other lesson I learned this weekend is that different paint types require different treatment. I tried the same trick with some primer, and it gave no coverage and ran all over the place.
That leads to lesson 3, always do a test panel to get the mix right, and test the mix in small batches so as not to waste paint.
Matt

[Wayne Jeffers]

Jeff,

If you want to substitute linseed oil for Penetrol (my father always used linseed oil), you want to use raw oil, not boiled.

Oil-based paint has chemical "dryers" added so it will dry in cool weather. This causes it to dry too fast in hot weather, causing the brush to drag, difficulty in maintaining a wet edge, and less than satisfactory leveling of brush marks. Adding Penetrol helps overcome these hot-weather problems.

Boiled linseed oil has chemical dryers, though in a lesser concentration than in paint. Since the point is to decrease the dryer/oil ratio in the paint to overcome the hot-weather problems, boiled oil serves this purpose less satisfactorily than does raw linseed oil, which has no added dryers.

Penetrol to paint: 10% should be adequate, depending upon the paint. You don't want to dilute the solids in the paint too much, although what solids you have to start can vary greatly from brand to brand.

Wayne

[Scott Rosen]

There are some things you just can't describe in words. You have to get some scrap and experiment with your particular brand of paint and the environment in which you are painting. What you want is something that will slow the surface cure down just long enough to let the brush strokes level.

There are two kinds of additives that will help. One is a slow-evaporating solvent. The other is a long oil. Penetrol is a blend of both of those things.

If you really want to slow down the cure, call the paint manufacturer and ask them what they tell the pros to use. Some paint companies will have a very, very slow solvent that they don't market to the general public.

[NormMessinger]

"...call the paint manufacturer..."

Are you kidding, Scott. Reminds me of the story of the Philosophers Club. Old philosophers sitting around philosophysing the question, "How many teeth hath a horse." Young upstart philosophers asked why they didn't just go get a horse and count his teeth. They threw him out of the club.

Kirby told me not more than 15% penetrol, if I remember correctly

--Norm

[Bob Cleek]

The point is, don't confuse Penetrol with thinner. As Scott says, this isn't something you can really describe in words. Let's forget for the moment the climatic issues. Just don't paint in the middle of the day in the hot sun. Figure to look for the same situation you'd want if you were waxing your car. If you can't get shade, at least lay it on before ten in the morning, if you can. Leave mixing up "slow" batches for super hot days and "fast" batches for the middle of winter to the pros who have to work no matter what the weather.

That said, your Penetrol shouldn't really go more than maybe ten to fifteen percent, although you can get away with a lot more without ruining things. Don't go past about a third or so, though. Use the manufacturer's recommended thinner for THINNING and use the Penetrol for improving leveling characteristics. (If you are in a hurry or cheap like me, you can get away with using a good high quality paint thinner, but increase the ratio of Penetrol to thinner, more {Penetrol) in that case... that seems to work.) I often end up adding as much as 100 per cent to the basic out of the can paint... maybe 50-50 thinner and Penetrol, which would give you about 25% Penetrol, all told. A dollop of this and a dollop of that until it is just right. The consistency you go for is somewhere between half and half and whipping cream. Thinner on the hot days and thicker on the cold ones. Lay the paint on fast and keep the wet edge working. Myself, as I've said before, I don't go for this rolling and tipping crap. The less you touch the paint after you slap it on and spread it, the better. The point of good paint and Penetrol, properly mixed, is that you won't get brush strokes because it will level. You don't have to wait for the paint to dry to test your mix. Just paint some on a test board WITH THE BRUSH YOU ARE GOING TO USE, just like you'd do when you paint the boat, and then set the board up in the same position as the area you are working on. If it's topsides, the board goes up and down. If it's decks, lay it flat. Watch the thing. It should level out perfectly in minutes, if not seconds. If you have brush strokes, and it looks too thick, add a little thinner and Penetrol and try again. Watch your bucket and see what the consistency looks like (and stir it well). That will eventually give you an "eye" for it and you won't need to do the testing as much. If it sags or runs, you are putting it on too thick. If it looks too thin, add a little raw paint. When you can slap it on and brush it out in five or six strokes and it lays flat... you're good to go.

[ 06-10-2002, 08:45 PM: Message edited by: Bob Cleek ]

[Jeff Kelety]

Thanks, gents. That last coat was after ten at around 70 degrees, though in the shady side of the boat for each coat. More of the flowing on stuff seems advisable.

jgk

[Greg Reiman]

Thanks for that info Bob:

I bought primer and paint from Kirbys, I have never seen such thick primer before. They recommended 10-15% penetrol but even with that much the primer still drags where your brush strokes overlap within 30 seconds of applying. The result is I will have to sand like hell before I put on the first coat of paint. If the paint is as thick as the primer was, I will probably go with at least 25% penetrol. I haven't used any thinner in the mix though, should I?

I am getting close to the finish line on my project and it is looking pretty good. I put six coats of varnish on the inside of the boat (1945 Thompson Zepher 15' cedar strip) I will post photos when I finish.

Greg Reiman

[Ian McColgin]

I've added up to 25% penetrol (back in the Goblin days, before I went latex) if it was really fast drying weather.

But you may want to work in a pair or even three folk. If one rolls (verticle) and the others tip it horizontal with nice brushes, you'll always have a nice wet edge bow to stern.

G'luck

[Scott Rosen]

George, I've found that when working with primer, Penatrol is not the best way to thin it. For some reason, adding Penetrol to a primer makes it harder to sand and doesn't really help the flow. I'd use a solvent like turps to get the primer to a smooth, easy brushing consistency. Then apply multiple coats, even if the prior coat is not fully dried. The last coat of primer should be flowed on to fill the brush marks left by the previous coats. Sanding between primer coats is pretty much a waste of time and paint.

[pcford]

Why not use the thinner that the manufacturer recommends? They want you to succeed.

Also Penetrol does not work with single part polyurethanes.

[Ed Nye]

This is the best discussion in a while.
I am no "Chemist". But, since the EPA has gotten into the paint design business, none of the paints seem to brush level the way they used to. They seem to "skin" over so quickly you can't brush them out. Cleek is right; you have to thin, thin and then thin some more. The light colors seem to brush out better than the dark, why??? I used Kirby's Bottle Green on Opal's topsides this spring. I thought I was never going to get that stuff thin enough to flow. The most interesting paint I have used in years. I almost gave up on it getting hard enough to tape (without a tape imprint) for the boot top line. The Cream went on the decks great, but took forever dry (not skin over - dry). It's like it gets dry to the touch in a few hours and then you can push it around (wet under the skin?) for a week or so.
I talked to a fellow at the Lake Union CWB Festival that has given up on the regular enamels for just that reason. He has gone to the one part polyurethane and slow reducers for just that reason. He says the reducer slows it down so it brushes and levels and the thin coat technology seems to allow it to dry.
Ed

[PeterSibley]

The painter at the yard where I sometimes work uses about 30% Penetrol, rolls on about a 4'x4' section then tips out....he gets an absolutely beautful job all in temperatures in the high 70's to mid 80s..........I'm calling from Australia, those are Queenland winter temps....I'd prefer not to paint in summer ! :D

[cbob]

In response to Ian and others. We roll horizontal, brush vertical (no sags using the caucasian system) with wide brush, takes two, three better for spotting holidays, work fast on the shady side, thin one part poly with manufacturers recommended thinner, only. What will the paint manufacturers response to a failure be, if Penetrol or any other non approved flow enhancing agent has corrupted his product? Right! Need two to move fast enough in Spring weather(which needs planning, not to be done on crappy days) on topsides 3.5 to 5 ft high.
With a little practice and care, the above will produce a job that will get the ultimate of compliments: Gee Bob, Your boat looks as nice as a 'glass boat, or better: How come they put a wood cabin on such a nice 'glass hull?
BTW, never have heard Kirbys mentioned around here (CA) or seen any on any shelf, but do have some Epafanes (paints) available. Could Kirby's be available through American Rope and Tar? Cheers , cbob

[cbob]

In response to Ian and others. We roll horizontal, brush vertical (no sags using the caucasian system) with wide brush, takes two, three better for spotting holidays, work fast on the shady side, thin one part poly with manufacturers recommended thinner, only. What will the paint manufacturers response to a failure be, if Penetrol or any other non approved flow enhancing agent has corrupted his product? Right! Need two to move fast enough in Spring weather(which needs planning, not to be done on crappy days) on topsides 3.5 to 5 ft high.
With a little practice and care, the above will produce a job that will get the ultimate of compliments: Gee Bob, Your boat looks as nice as a 'glass boat, or better: How come they put a wood cabin on such a nice 'glass hull?
BTW, never have heard Kirbys mentioned around here (CA) or seen any on any shelf, but do have some Epafanes (paints) available. Could Kirby's be available through American Rope and Tar? Cheers , cbob

[Art Read]

Kirby Paint Company (http://www.kirbypaint.com/)

[imported_Steven Bauer]

Is the 'conditioner' I bought from Kirby's the same as Penetrol? That's how I've been using it.

Steven

[Wild Wassa]

One contitioner that I have, is a rub-on after the paint is dry. It needs a soft cloth. Another conditioner that I have is only a thinner. This post is a bump, I didn't find anything on the Kirby's site describing their conditioner.

I haven't used Kirby's conditioner. Kirby's price for a gallon of enamel is excellent, it's 1/2 the cost of Aquacote poly. Kirby's should have a retail outlet in Australia.

Warren.

ps, In International's painting boats booklet, it's just a freeby, in reference to their w/b poly, it says, "you can drink our thinners."

[ 01-28-2004, 02:46 PM: Message edited by: Wild Wassa ]