Gluing back peeling paint

by David S. Lawyer mailto:davylawyer1@gmail.com

Oct. 2015. Minor edits: Nov. 2015, Jan., May, Sept. 2016, July 2017
Explains how to glue back peeling paint and prevent more peeling using a "peel primer" or the like. Presents various options of fixing peeling paint. While it's mainly for wood surfaces, some of it is valid for other surfaces.

1. Introduction

2. Conventional fix: scraping off old paint

3. Treatment depends on the paint condition

4. Applying paint, peel primer; glue?

5. Clamping down (or pushing back) peeling paint

6. Using weights (on horizontal surfaces)

7. Clamping pads and cauls

8. Sanding after gluing

9. Filling in depression in paint

10. Paint brushes and paint jars

11. Rain and blow dryers

12. Where to work on doors, windows and wood screens

13. Concluding remarks


1. Introduction

When paint is peeling or cracking, the conventional fix is to remove the loose paint by scraping etc. and then repaint. But there are other (often better) alternatives using a liquid paint-glue-primer. One brand name is Rustoleum's "Peel Stop" which the Co. describes as a "Clear binding Sealer". Another brand is Duckback's "P3 Peeling Paint Primer". From now on this will be called "peel primer". It's like a thin glue which is painted onto (and into) cracks in paint that is threatening to peel or is actually peeling in some spots. It's thin and seeps into the tiny spaces underneath the old paint and glues the loose paint back. If some paint has already started to peel and has visually lifted up from the surface, then to avoid pits in the surface, it's necessary to push it back down after peel primer has flowed under it. Then one may need to use clamps to hold the old peeling paint down against the peel primer underneath the peeling paint so that such paint will stick.

2. Conventional fix: scraping off old paint

Old Paint may be removed by scraping, sanding, wire brushing, power washing with water, etc. If you are removing old lead paint you should take care not to breath the toxic lead paint dust and to keep the old lead paint out of the environment. For sanding, wet sanding or sanding using a vacuum dust bag and a special filter will help prevent lead dust from getting into the air. Scraping is likely to produce some lead lead dust (in addition to lead pains chips). Using peel primer as an alternative to scraping off old paint, reduces the need for scraping and/or sanding and thus helps deal with the lead problem. In most cases today old lead paint will only be found underneath layer(s) of non-lead paint.

But even if you are removing all the loose paint you still usually need to use peel primer. The old Paint that seems to be still firmly attached may not be fully attached to the surface in spots and may peel off years later. To reduce the future peel, you can apply peel primer so that it will seep under the edges of the top layer(s) of the old paint which remains after scraping off the loose old paint. The peel primer seeps under the edges of the remaining paint and glues it on so as to stop further peeling.

3. Treatment depends on the paint condition

A point on an old painted surface can be in one of three different states: 1. Paint OK 2. Paint has separated from the surface and is curling away from the surface (paint is peeling off) 3. Paint has already broken off from the surface, leaving an indented scar (paint has already peeled off)

A certain area may be classified as follows:

4. Applying paint, peel primer; glue?

4.1 Introduction

Peel primer is thin so that it can seep into tiny cracks. But since it seeps also into old wood, you need to apply a lot of it and give it some time to seep under the old paint and into the surface under it: wood or old layers of paint which itself may have cracks in it with wood underneath. Besides painting it on with a paint brush (or smaller artist's brush) another method is to rub it into the cracks after first painting on a heavy layer over the cracks. Still another alternative is to use a plastic putty knife to work it into the cracks.

4.2 Rubbing in peel primer and paint

When using peel primer to get into tiny hairline cracks, one may often get more peel primer into the cracks by rubbing it in. One can use ones fingers for this and even bare fingers seem to work. One can apply a daub of peel primer with a paint brush and then rub back and forth transverse to the cracks to rub it in. If one is only doing a few tiny cracks and doesn't have a wet paint brush handy, one may simply dip the tip(s) of ones finger(s) into the peel primer and then rub it in, possibly twisting a finger (and wrist) so as to use up all the peel primer on the finger. For larger areas one may use all 4 fingers (except the thumb) to rub in peel primer. One may also need to sometimes rub in the direction of the crack to redistribute the peel primer on the surface, especially for a vertical surface where the peel primer may run down the surface due to gravity. An advantage of rubbing in peel primer is that it puts most of the peel primer into the cracks with little peel primer left on the good surfaces which might slightly discolor/stain such good surfaces if you are not going to repaint.

If you rub it in well, you may see dirty peel stop adjacent to the crack. This is dirt that flowed out of the crack and you have in effect, rinsed dirt out of the crack. This is both good and bad. It's good because now the crack is now cleaner inside and peel primer (and paint too) will better adhere inside a cleaner crack. But it's bad because now you may need to wipe dirty peel primer up with a rag or paper towel. If you don't wipe it up fast, the very thin layer of dirty peel primer left on the surface (outside the crack) will rapidly dry and leave a dirty looking spot.

Also, one may rub paint into cracks, although it's best to first use peel primer unless the cracks are only superficial and don't go into the wood. After the paint dries, you may need to redo it as some cracks may come back. One way to deal with cracks that are likely to come back is to rub thicker paint into them after first rubbing in thinner paint which will seep into the cracks better. But you don't need to buy thick paint, just let the ordinary paint dry a little so that it becomes thicker but still remains soft. As the paint becomes thicker, rubbing hard will produce heat and make the paint even thicker, almost hardening the paint in the cracks./

4.3 Dried Peel primer absorbs dirt

Any peel primer left on a surface will absorb dirt over a period of time and look bad. Peel primer belongs in cracks and under paint (old or new) and not on a surface exposed to the elements (such as dust in the air). So be sure to wipe up any peel primer from any exposed surface after giving it a minute or two to seep into cracks and damaged areas. Use a damp rag or damp paper towel, etc.

4.4 Type of paint to use

For the first coat of paint over peel primer, using a paint that contains a primer (or what amounts to about the same thing: using a solid color stain) may be a good idea. You may have porous wood under cracks because: either you didn't apply enough peel primer or you missed putting peel primer in a crack (for various reasons such as: you ran out of it, it wasn't handy, etc.). The primer will adhere well to porous wood and also glue back peeling paint. But it will not seep as deep into thin cracks as peel primer does and thus peeling may be more likely to happen again at these spots.

Should you use low gloss or high gloss paint for the final applications? High gloss is claimed to absorb less dirt and is more resistant to washing. But low gloss or flat paint will hide defects better and will eventually self-clean itself by chalking. The author's choice is either semi-gloss that contains primer or high gloss. For touch up work it's probably best to use whatever gloss of paint was originally used on the surface.

4.5 Brushing on paint; no drips

One problem with brush painting is that paint may drip off the brush before you get the brush to the painting surface. You may have read that you should tap the brush on the inside of the paint can or jar so as to remove excess paint and prevent dripping from the brush. But the more paint you keep on the brush, the longer you can paint with it before having to re-dip it in the paint again. Instead of removing excess paint after dipping a brush, you can spin the brush to keep drips from forming. There are a few ways of doing this: you may turn it with your fingers of just turn your wrist back and forth. If you use your fingers, it's easy to do this with a round brush handle. When such a brush first hits the work, it releases a lot of paint and one needs to spread out such paint.

4.6 Cleaning brushes

If you want to put less paint down the drain, try to use up most of the paint on your brush before cleaning it. Also, when done painting, put some water on your brush and brush on a large dry surface that uses this paint (which is now very thin). To get out most of the paint from the heel of the brush, hold the ends of the bristles tightly between your fingers and shake them so as to work out stuck paint while frequently letting water run into the top of the bristles. When painting, try to minimize the amount of paint that works its was into the heel of the bush by only dipping the bristles about half way into the paint. Of course, if the bristles are short you may need to dip them in further.

5. Clamping down (or pushing back) peeling paint

5.1 Overview

There are many different ways to push back peeling paint. One way is just to push with ones finger, hold, and hope it will not pop back up. Another is to sand the surface before the peel primer is completely dry under the old paint and the pressure of the sand paper pushes back some of the paint. But the surest method is to use clamps (like you would use for gluing boards together).

5.2 Pushing peeling paint back with ones fingers

If one pushes back peeling pant with ones finger(s), it will sometimes stay pushed back and sometimes it will pop back, often not jutting out as far out as it originally did. Sometimes it only pops back after a delay of seconds to minutes. It seems that with heavier glue underneath the paint, it's more likely to stay pushed back. This suggests a two-application method for such a surface: First paint with peel primer get it into the small cracks and then use heavier glue (or triple thick peel primer) under the cracks that are lifting up. Then push back on the lift-ups until they stay pushed back.

Also, letting the peel primer dry a little before pushing may help. Another trick to help prevent the chip from popping back is to push with the edge of a fingernail(s) and hold for a few seconds. This will put extreme pressure on a small area and you hope that the wood underneath doesn't get (slightly) damaged. You should experiment and if the chip pops back but still has wet peel primer under it, it may stick on the second (or third try) without applying more peel primer. Even if it stays stuck, it might help prevent peeling in the future if you work more peel primer into the crack, especially if the crack appears to be slightly open.

5.3 Using clamps

One may use wooden boards as clamping pads. After applying peel primer to an area over which a clamping pad will go (where the paint chips were lifting up), the author started the clamping work by placing wax paper over this area. The surface may still be wet with some residual peel primer. Then he placed a board (the clamping pad) over the wax paper and used clamps (such as C-clamps) to hold this board down tight on the wax paper and peeling chips of paints. After several hours, remove the clamps and wax paper. Of course, the wax paper is to prevent the peel primer that remains on top of the old paint (both peeling and not peeling) from sticking to the clamping pad board (which is called a clamping "pad if it's small and a "caul" if it's large). See clamping pads

5.4 "Clamping" without clamps using springs and wedges

Sometimes it's feasible to clamp by just using a wood board as wedge or spring. For example, to glue back a paint chip on one side of a window jamb. cut a lath (thin board) so that the length of it, plus the length of the two wood clamping pads that you'll use with it, is a little longer than the width of the window jamb. Then install this lath horizontal with a pad on each end to prevent the lath end from scratching the window jamb on one end and to provide uniform pressure against the peeling paint chip(s) on the other end. But since the length of this 3-piece clamping contraption is slightly longer than the window width, it won't fit. However, if you think about it there are two ways to make it fit:

The pressure on the pads not only presses back the peeling paint but also keeps this 3-piece clamping contraption from falling down onto the window sill. If using the wedge method, take care not to wedge it too tight when the lath is nearly horizontal where the leverage ratio would approach infinity if all the wood was absolutely rigid and had no elasticity. Too much force can even bend weak window jambs, etc. Instead of lath, one can use other thin boards such as strips of wood cut from wood shingles or the like.

6. Using weights (on horizontal surfaces)

If the surface you are gluing back is level (or somewhat level like a sloped window sill) one can use weights instead of clamps. For example, one could take a one-inch-square homemade pad and set a (sealed) quart can of paint, etc. on top of it. A steel dolly" used for removing dents in automobiles makes a good weight.

7. Clamping pads and cauls

7.1 In general

When you use a real clamp, the two parts of the clamp that push on the wood are called pads and are usually metal. But many clamps have pads that are not large enough to cover an area of peeling paint so you need to place a block of wood on the clamp pad to, in effect, increase the area of the clamp pad. This block of wood may also be called a "pad" but if it's large (say a foot long) it's called a "caul" You can make your own clamp pads and cauls from scrap lumber. High quality plywood works well for small pads but wood boards work OK also. You may also use non-wood pads such as hard and flat plastic objects or thick rubber pads. High density sponge rubber pads (such as used for a bicycle seat) are good for gluing back paint on non-level surfaces such as curved wood molding.

Pads and cauls not only serve to push back the peeling paint but are often placed under the opposite pad of the clamp in order to prevent indentations in the wood on the side opposite to the peeled side. In some cases you may have peeling on both sides and use cauls or pads on both sides of the work.

7.2 Cambered (curved) cauls

If you have a narrow stretch of peeling paint a few feet or so in length, you may place a wood board (say a 1"x2" board a few feet long) over it and then use s few (or several) clamps to clamp down the caul since you must press down almost uniformly along all the length of the peeling section. But there is a way to do this with just one or two clamps and that is to use a caul that is cambered (or bowed) like a cross-country ski. When skiing on such a ski, the weight on the skier's foot is distributed on the snow along the entire length of the ski. This is because the ski is cambered and the foot bindings rest a few inches above the snow when the skis by themselves are placed "flat" on the snow (or ground) with no skier's weight on the ski. For the cambered caul board one places it (like a ski) over the peeling paint strip so that there is some air space between the middle of the caul and the peeling surface. Then one uses just one clamp to press down on the center of the caul and close up this air space, thereby applying uniform pressure on the old paint along the full length of the caul. To do this quick, push down on the center of the cambered caul with your hand as far as you can and then slip a clamp over it and tighten. Alternatively, one may turn just the caul upside down so that the caul ends are above the peeling work and then use two clamps, one at each end of the caul.

When clamping, do you need a caul or pad on the other side of the work, to take the pressure on the non-peeling side of the work? No, if the work is set on a table top or if you can't access the non-peeling side of the work (such as a door/window jamb). But in other cases you might need such a backing caul to prevent the work from bowing (if it's weak). It's not much extra work to do since you otherwise might need to place a pad there to prevent the clamp pad from marring the wood.

How do you get a cambered caul? You might use an old ski that has a lot of camber in it (for cross-country skiing, etc.), or find a board that is defective and has camber in it (a lumber yard might give it to you), or use steam to bend a board. You might try wetting a board and then clamping it with a block in the center (I have never tried this) like how cross country skis are stored to maintain camber.

8. Sanding after gluing

After the peel primer has dried, often several hours or more, you can sand the surface before painting. If there is a possibility of sanding down to lead paint, you may use wet sanding. For hand sanding, use a sanding block such as a block of wood, a plastic block of some type, or one from a hardware/paint store. If you want to sand and create a level flat surface, use a ridged sanding block instead of a flexible rubber one. There are some that have wooden handles and are used for auto body work.

9. Filling in depression in paint

When chips of paint fall off wood they leave depressions in the painted surface where the chips used to be. Often, they even take a small amount of wood with them (look at the back of a fallen-off chip). And there is often more than one layer of paint that chips off, which leaves a deeper depression. Even after painting over the depression, it is often very noticeable. Should you fill them in to make it look better or just live with the depressions? Filling them in is not easy and this is one argument in favor of pushing back old paint back so as not to leave depressions. I've been told that the best filler for such depression is just more paint. Spackle is not designed for this purpose. It may not stick on very well, and might be difficult to sand off if it does stick. Some claim that wood putty will work OK but will it stick well to previous paint?

If you are using paint to fill, putting on more paint thickly is often not easy. If you can get the work surface in a level position then you can daub paint into the depressions. Use thick paint and make sure the paint level is higher than the surface of the non-chipped paint. This is to allow for shrinkage as the paint dries. If the surface is vertical, you will have problems with paint running down the surface. You can periodically push the runs back up to the depression as the paint is drying (a putty knife may be best for this). You don't have to constantly watch it, but return to it every few minutes at first and every several minutes later. Overhead paint is easier than vertical and often doesn't drip down like you suspect it would.

One can also apply paint to depression with a putty knife (a plastic one may be better than a metal one). This creates a level surface but when the paint dries it may still be depressed due to shrinkage, but not as depressed as was originally. At first, press normal on the putty knife to adhere the paint to the surface and then apply more paint and press lightly over the depressions so as to get the paint level higher over depressions. Of course, you don't want to leave much paint over the non-depression area. Whether or not you use a putty knife, you need to sand the spots level after the paint has dried (or just sand the whole surface including the spots you filled).

10. Paint brushes and paint jars

10.1 Paint brushes

For painting small areas (including "touch up"), which is often the case with peeling paint, one may use artists' paint brushes obtained at an artist supply store. The brushes are used both for applying peel primer, and for applying paint. Make sure that the paint brushes are narrow enough to fit (with some clearance) in the top openings in your paint jars. There may be cases where you just need to paint peel primer in a narrow peeled depression spot and a tiny artist paint brush about 1/8 inch in diameter, may be just what you need. With small brushes you can sometimes feed the bristles (saturated with paint) under the lifting paint to get peel primer under the old paint. A tiny brush also comes in handy for touch up of tiny spots. A small dot of new paint that is slightly off-color will not be very noticeable on a background of old faded paint. I have larger flat brushes about 3/8" and 3/4" in width as well as a round 3/8" brush. Such brushes should not leave any brush marks like some paint-store brushes do. I also have a wide artist brush about 1 1/2" wide which I think does a better job than a paint-store brush of the same size.

10.2 Paint jars

It's handy to have paint and peel primer in small jars that have a screw-on cap that can be readily opened. These are useful not only for small jobs but for work where most of the time you are waiting for the paint, etc. to dry (while doing something else). This makes it convenient when postponing a job by just screwing on a cap instead of having to pound on the lid of a paint can (and preventing the groove on the rim from scratching and rusting by using linseed oil or plastic wrap). A small, one or two ounce jar of paint is easier to hold when you are on a ladder, etc. You sometimes can buy small paint jars at an art supply store. The best are made out of glass (hard to find). Honey sometimes comes in small glass jars which may be later used for paint.

When a jar's gasket starts to fail you can replace it with rubber cut from an old bicycle inner tube or from sheet rubber you can buy at a hardware store. Also, to keep the caps from sticking (and being difficult to open) you could put linseed oil on the jar threads. Vaseline also works but take care not to get it in the paint. For hard-to-open jar caps, use a thin rubber pad used like a rag for grabbing stuck caps on food containers. If it still will not turn, you can heat it with a propane torch. Peel primer is the worst "paint" for cap sticking and since it has water in it and a metal cap will rust easily unless you protect it with some kind of lubricant. A convenient jar to use is one where the jar diameter is almost double that of the cap since the top of the jar is dome shaped (but I was told they are not sold without artist's paint in them). When paint gets stuck in the groves of the cap, you can scrape it off with a small screwdriver. When carrying a paint jar, if you hold it up straight and don't tilt it, paint is less likely to get into the cap groves and cause sticking. Not filling the jar completely when you refill it with new paint will also help prevent this. A few days after you close a paint jar, you might try to start opening it. Periodically unscrewing the caps a turn or two will help insure that the caps remain easy to open. Remember not to tilt the jar much when removing the cap.

But a drawback to using small paint jars is the problem of filling the small jars with paint. There are pouring guides for metal paint cans made of plastic but these guides must be carefully installed and get paint on them that needs to be cleaned off after use. Another way of transferring paint is to ladle it out using say a measuring tablespoon and tilting the paint can as needed. Ladle (or pour) the paint when you are just ready to start painting and use a clean paintbrush to clean off the tools (the ladle, etc.). When this paintbrush is saturated with paint, paint with it and then brush off some more paint off your tools, etc. Then finish cleaning the ladle with water, etc.

11. Rain and blow dryers

When paining outdoors, if rain is threatening and you need to dry the paint or peel-primer fast, use a blow dryer (unless the area to dry is too large). You can even paint in light rain using a blow dryer (normally used for drying hair). However, if too much moisture gets into the dryer, it may short out and stop running due to an internal fuse that hopefully will restore itself when the dryer dries out later on. It might also trip a ground-fault interrupter in your home which you must reset (push a button) to restore power. Of course the best solution is to paint well before it rains but if you want to protect exterior wood from rain damage: "better paint late than never". If it's cold and humid at night) dew may form on just-painted surfaces, diluting the paint and making it stay wet all night and thus easy to wash away with the slightest rain or drizzle.

12. Where to work on doors, windows and wood screens

For easily removable windows, doors, and wood screens, it's best to remove them (if it's easy to do) and work on them on a workbench or card table. This way they become horizontal and one can apply a lot of peel primer and paint without having some of it run down the wood. Some doors and casement windows remove by just pulling out pins.

13. Concluding remarks

Gluing back peeling paint can be a lot of work. But if you just have an occasional small spot or two that starts to peel, unscrewing a couple of jar lids and using small paint brushes might fix this in minutes. Peeling is usually caused by moisture getting into the wood and solving the moisture problem should be top priority. You may need to carefully inspect for peeling fairly often, depending on circumstances, and stop the peeling before more moisture gets into the spot that is peeling and makes the peeling worse. Situations vary and the suggestions in this article don't fully apply in all cases. There are likely many situations not covered by this article but you may be able to figure them out, possibly by experimenting with various solutions. You need to apply common sense and deviate from what is suggested in this article when feasible. Remember to use wax paper when clamping to keep the pads/cauls from sticking to the work. Even if the surface appears to be free of peel primer, clamping may squeeze out such peel primer hiding under the old paint.