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Varnish Removal with Heat Gun
|Author||Topic: Varnish Removal with Heat Gun|
posted 05-14-2002 08:51 AM ET (US)
Someone in an earlier post suggested removing Varnish with a heat gun. Has anyone tried this? How well does it work and what technique do you use? I need to refinish my seat and I really would like to avoid sanding the finish off.
If I ever find a RPS for sale, I will replace this wood seat with it!!!
posted 05-14-2002 08:59 AM ET (US)
Ron, I don't know about a heat gun. But a good quality stripper will work to get most off. Then the sanding would be minimal. Regards, Jay P.S. Even if a heat gun works you will still have to sand:(.
|Tom W Clark||
posted 05-14-2002 10:38 AM ET (US)
A heat gun works very well. Varnish is much easier than paint to remove with this method so if you've ever stripped paint with a heat gun you are in for a pleasant surprise.
The idea is to use the heat gun to soften the varnish while you simultaneously peel the finish up with a tool like a putty knife.
Actually, the tool I use is what is variously called a "painter's multi purpose tool", "four-in-hand", "five-in-hand", ect. It looks like a big putty knife with a hook knife on one side and a semi-circular cutout on the other for wringing paint from a paint roller.
The blade in front is stiffer than a putty knife and is usually somewhat sharpened. Blade width may be 2 1/2" to 3" wide.
Start at one end of the piece of wood you are trying to strip. I am right handed so I hold the heat gun in my left hand pointed at the wood with a bit of an angle so the hot air glances off to the left away from the the knife. In my right hand I hold the knife behind but immediately adjacent to the area of finish tha has just been heated.
If you are coordinated, the heat gun will soften the varnish and the knife will lift it in one move as you move down the piece. The varnish should peel up in one continuous strip.
Do not stab at it! If the varnish is not soft enough to come up it needs more heat. Poking or stabbing at it will lead to the knife digging into the wood. Be careful of lifting grain and creating huge slivers.
It takes a little practice but its a short learning curve and soooo much healthier than creating a huge cloud of dust. Under the correct circumstances, the varnish will be removed much more gently than just grinding it off.
Once the varnish is removed you will still have to sand it smooth and take care of small areas of residual varnish but done correctly, heat gun removal or "burning" the finish off, will get all the varnish off in one pass of the knife.
posted 05-14-2002 03:38 PM ET (US)
Ditto to Tom's comment. The heatgun is very effective in crevices, just dont overheat because the wood will discolor and even burn.
posted 05-14-2002 09:04 PM ET (US)
Tom hit it right on the head. Heat gun all the way and if you can get one that you can adjust the heat for. The one I use allows you to close the air inlet dampner on the side to adjust the amount of heat you desire.
posted 06-20-2002 09:21 AM ET (US)
I got a neat Milwaukee Variable Temp heat gun for Father's Day and last night I started removing the varnish from my helm seat with it. In the past, I have always done this by sanding. This "heat method" is great! The varnish comes off kind of like scotch-tape and the wood is left intact! Varnish removal by sanding has always bothered me because of the wood that gets removed in the process. This heat method will only result in wood loss from the finish sanding. Thanks for the tip.
posted 06-20-2002 12:11 PM ET (US)
Tom Clarke or others,
I've had a little different experience with heat guns, maybe you can help since some of you are big fans of them. I've found that heat guns only take off the top layer of varnish. The varnish that is "deep down in the grains" doesn't come off. I've found even after sanding, varnishing looks really weird because old varnish is still present down in some of the grains, and new wood is exposed on the top. The results are I get yellow streaks in the grains that don't match the freshly sanded wood.
I've found the only way to get a nice uniform finish is to chemically strip the old varnish off.
Don't get me wrong, I'm not a fan of using paint stripper, but it has been my experience if you want it to look good, it's the only way to go. (Aside from sanding like heck and removing a lot of wood.)
Thanks for any input,
posted 06-20-2002 01:07 PM ET (US)
I also agree with the heat gun and have used it to strip an entire house worth of paint and varnish. Instead of using the tools prescribed above I use a correctly sharpened cabinet scraper, which is a straight piece of flexible steel with a sharpened burr on the edge. When held in your hand and flexed, it is used to create paper fine shaving from wood. It works great on removing a finish that was softened from a heat gun. For an open grain wood like mohagany, you may need to go back over the wood with a chemical stripper and a brass brush the size of a tooth brush but this will get it all. Lightly sand and your done.
posted 06-20-2002 01:14 PM ET (US)
As a point of reference, I called a local wood stripping place yesterday, and they said they would dip strip all the wood in my 15' SS for ~$100. After they finish their work, the only thing they said I would need to do before varnishing would be a light sand.
|Tom W Clark||
posted 06-20-2002 01:41 PM ET (US)
For the record, my name is Clark not Clarke. I get that a lot but I feel it is better to “nip it in the bud” before it causes more confusion.
Every piece of varnished wood work is going to be different. The tenacity of the varnish will be dependent upon many factors including the type of wood, type of varnish, condition of the wood when varnish was first applied, and operator skill with a heat gun.
I agree that no heat gun will remove all the finish without the need for some sanding afterwards. Nor will a chemical stripper.
If a piece of wood was new and smooth when varnish was first applied, the varnish will come off nicely. I have found older woods that have had finishes previously applied and then stripped off before varnishing are much more difficult to remove.
Using a heat gun is a mechanical means of removing varnish and as such is limited to the tool being used for the scraping. A straight edged tool cannot get down into any low spots or into the grain of the wood itself.
A piece of wood that has some flat grain and which has been sanded many times before will tend to have high spots where the hard grain is and low spots where the soft grain is. Stripping a finish off of a piece of wood like this is going to be more problematic. Likewise, a piece of wood that has a lot of exposure to sunlight may develop checking which will hold the finish down deep. A heat gun cannot remove this finish.
A heat gun will not remove a stain that has been applied to the wood before varnishing. Chemical strippers will not necessarily do so either.
Regardless of the technique used to strip the varnish, sanding will have to be used to get the face of the wood flat and uniformly smooth in order for the new varnish and/or stain to be taken evenly. It is perfectly acceptable to apply a chemical stripper after the bulk of the varnish has been removed.
Some pieces of wood require this as they are too delicate to withstand much sanding. In these cases, it is sometimes necessary to abandon any hopes of getting the wood perfectly flat again. This is the case on one of my boats that has a lot of varnished mahogany plywood.
A heat gum is a great way to remove most of the finish on anything painted or varnished. It will not work on everything. Experimentation are required to ascertain whether it will work. Believe me, you may have to use many different techniques to get where you want it be. I have several chemical strippers in my shop as well as six different power sanding tools and two heat guns. They all have their place.
$100 sounds like a great price. Be careful though. Commercial dipping services can be VERY hard on the wood. Again it is dependent on the wood in question, but they can really eat the hell out of the grain. Ask to see a sample of the same kind of wood as you are contemplating having dipped.
There used to be a dipping service here in Seattle called The Furniture Spa. (I always loved that name.) They were there for decades and I used them for a variety of stripping jobs from trailer wheels to architectural millwork. There's no way they would have done an entire 15’ SS interior for $100. If they check out, GO FOR IT!
posted 06-20-2002 05:03 PM ET (US)
Sorry about the extra "e". (Have I done this before?) I know how to spell your last name. I just went too fast, and of course spell check won't catch that mistake.
Thanks to everyone for the hints on the heat gun. I just wish there was a "one-step" process. Maybe there is... "flat black house paint"...
posted 06-20-2002 05:52 PM ET (US)
My house doors have all spent time at The Furniture Spa. Ever noticed that the owner seems to have suffered some from the fumes?
One thing about dip tank stripped wood is that it comes out with the grain raised and really bleached out. So you might need more than a 'light' sanding. But the damage to the wood structure makes the bleached grey stuff come off easily, so its not too bad.
posted 06-20-2002 08:28 PM ET (US)
Great Topic and Posts, I will be re-doing my wood soon, and these suggestions will be very valuble when I start. Thanks to everyone for their posts and suggestions!! Jack.
posted 06-20-2002 09:26 PM ET (US)
I just finished revarnishing the pilot seat in my Nauset... I used the heat gun method as all the strippers I had tried failed to do very well at all... I'm not sure what varnish was on the thing but it would not come off without the heat gun... I had to heat the wood darn near to the burn point before it would let go (even with a new 1" putty knife)... I then sanded the heck out of it (after the varnish was removed) to get down to un-sun-bleached wood grain (be carefull on the plywood though)... I then gave it a coat of stain and then sanded most of it back off... Then the varnishing (7 coats)... The result of all this effort is wood that looks better than the day I got the boat (back in 1985)...
posted 06-21-2002 01:19 AM ET (US)
I like your idea of asking to see a piece of the same kind of wood at the strip joint (hehe), but I'm guessing he's not going to have a piece of Philippine Mahogany laying around, right? This place is called "The Big Dipper" (here in Portland, OR), and stripping is supposedly their main business, so maybe he will have a piece. Alternatively, he could do a small piece of mine first to see how it turns out.
I've heard of chemical stripping methods drying out the wood, making them brittle and more susceptible to warping. I've heard of some using some kind of moisturizing solution, or some kind of wash, after chemical stripping and prior to varnish. I've chemical stripped a few pieces, haven't done any post-stripping treatments, and haven't had a problem, but have you ever heard of this?
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