|HU Curriculum - Blow Mold Curriculum|
Repainting a Blow Mold
With Spray Paint
By Carrie Sansing
Various sizes of good quality masking tape and/or automotive detail tape
Cheap plastic bags (free grocery bags are great)
Optional: Liquid Mask, sold as liquid latex, and Frisket masking film (both are available at art, hobby and some craft stores also on the internet)
Optional: Crayola Model Magic
Krylon Fusion for Plastic spray paint (KFFP)
Before you Begin
You’ve stripped your blow mold down to white? It’s squeaky clean and ready to go? No? Read the Stripping blow molds How-to here <click here>
Where do you start? Take a good look at your blow mold. Determine how many colors are needed. How much detail will be painted? What do you paint first? Are there very large expanses of the same color, such as on a Santa Claus, where there is a predominant color. The amount of detail and number of color changes will guide you as to what areas need to be painted first. Painting this snowman, for instance, would require black, red, and green paint. White plastic never needs to be painted white. Surprisingly, many of the molds I have bought and restored had their white areas painted. I have stripped more molds of white paint than I care to remember, so don’t do it, it’s almost always unnecessary.
You have your supplies and you’re ready to go. Make sure that you start your project in a well ventilated area or outdoors. Be careful to cover up anything that is nearby your blow mold. Overspray and paint dust is guaranteed; it will settle on the areas around the blow mold. So if you don’t want paint on the walls, floor, grass, or surrounding areas, cover everything. Many years ago, I spent a long, hot, afternoon washing flecks of red paint dust off the hood of my blue car.
Since that time, I have built a spray painting booth from PVC pipe and plastic sheeting. It breaks down quickly for storage. If you don’t plan on repainting many blow molds, there is no need to go to the expense of building one. But if you plan on doing a lot of molds, a spray paint booth is the way to go. You’ll be spending between $75 and $100. I created mine using a modified version of this design. It’s an excellent how-to: http://www.wikihow.com/Create-a-Paint-Booth-in-Your-Garage
If possible, create your painting area on a work bench or covered table. It’s much easier to paint the blow mold by elevating it. If you can’t, work on a level area of ground or the floor, but you will be on your knees or in a squat position when painting.
I recommend that you wipe down your blow mold with alcohol and a paper towel right before you paint. This insures that there are no contaminants whatsoever on your blow mold. Dust, grease, fingerprints, anything on the surface of the plastic is going to be there when you paint and will affect the paint job. Alcohol will remove these contaminants; it evaporates quickly and will give you a completely clean surface to start.
The Paint Plan
Economy, both in dollars, and time spent doing a restoration is important. Although it is often necessary, try to avoid having to tape over or mask off newly painted areas. Although KFFP is extremely durable and is formulated to adhere to plastic, it requires a good amount of cure time. It’s frustrating to have spent a lot of time carefully taping off an area, painting it, and then having to tape over this area. Sometimes, no matter what you do, that new paint may come off. Keep this in mind as you design your paint plan.
Generally speaking, plan to paint the largest expanses of color first and tape off your details. This is not a hard and fast rule, however; it depends upon the blow mold. If a face is to be done, I usually leave that area for last.
These candles were an easy project, requiring only two colors. The decision of what to paint first was simple, the large red areas. Why not do the detail first? The amount of time and materials needed to cover up the candle itself would be excessive. Use a common sense approach. Using masking tape, I taped off all the wax drips, the spiral, and the pine cones. I covered all the areas I wanted to remain white or that may have been in the line of fire of the spray paint. Depending upon the mold you do, it’s important to have a paint plan thought out ahead of time. Otherwise, you will be masking off and repainting areas that would not otherwise be necessary.
To mask a large expanse, use a plastic garbage or grocery bag to cover those areas. You don’t waste tape and you save a lot of time. Depending on the blow mold, I will often put the entire mold into the bag, rip out parts of the bag to reveal the area I want to paint, and then tape the edges of the bag down. As you tape the plastic on, press the tape down hard. You don’t want any spray paint to seep under the edges of the tape and onto your blow mold. If this happens, you will see dried paint under the tape when you remove it..this is known as bleed.
Also when taping, butt the edge of the tape up against the edge of the raised surface to be painted. In the picture of the candle, look at the spiral. Notice how the tape is flush up against the bulge of the candle area to be painted. This is the technique I use to guarantee a very crisp straight line with no overspray. Start to mask off all the areas that will NOT be painted first. In the case of these candles, I covered all the parts that were to remain white, leaving all parts to be painted red, exposed. Be careful in this step, it will make the difference in the long run. You do not want overspray on the other areas.
As you apply each run of tape, make sure the tape is sealed well. If you have long fingernails (which I do), run a nail along the very edge of the tape and press firmly. If you don't have long nails, use the tip of a screwdriver or other tool to do this. From start to finish, I was able to tape off this candle in approximately an hour and a half. I prefer to use tape, and with experience you will be able to do it very quickly, but others find it tedious and slow to work with.
A good friend of mine, Shawn Johnson, came up with the idea of using Crayola Model Magic. Work it with your hands until it is soft and elastic and rough it into sheets. Then press it down over the areas you want to cover. When I’ve used it, I trim it with a knife to achieve clean straight edges. It does allow for more bleed than tape though, as it doesn’t adhere as tightly. I find it good for small areas of detail, such as eyes, mouths, or when doing custom paint jobs. Depending upon you’re level of “fussy”, you may like using it and join the ranks of those that are happy with the results.
In conjunction with tape, I also use Liquid Mask, especially when using an airbrush. Liquid Mask is applied with a regular brush or with an airbrush (although it needs to be thinned for airbrushing). It is painted on the areas you want to cover, you allow the Mask to dry, and then paint your blow mold. After painting, the Liquid Mask is simply peeled off. The advantages to Liquid Mask are that you can achieve very precise detail, there is no paint bleed and it is fast to use. The disadvantage is cost, being the most expensive of the masks I use. Personally, I recommend Bob Dively Liquid Mask for detail masking as it does not get rubbery for 7 -10 days after the bottle is opened and exposed to air. There are many other brands of Liquid Mask available. Parma is also very good, but will start to rubberize within 5 -7 days after you open the bottle. I recommend that if you decide to use a Liquid Mask, work quickly when painting it on. Apply a thin horizontal coat. After that coat dries, apply again, going vertically over the same area. The trick is to brush it on thin and use two coats going in different directions. Doing it this way insures that it will dry fast and that you have a completely sealed surface. After you have painted, lift an edge and peel it back and off.
The final alternative to tape is Frisket masking film. Frisket is a clear film with an adhesive back. It’s quick to use and will give precise crisp lines. It is rolled on, smoothed, and the areas to be painted are trimmed out with an x-Acto or craft knife.
In this example, I applied the Frisket to the entire top of the Sign and cut away the areas I wanted to paint. The recessed words “North pole” as well as the stripe around the edge were the areas I removed.
Again, this is a more expensive method than using tape but does allow for superior results fairly quickly. Frisket will stick to itself once you pull it off the roll. So have your blow mold ready and pull the Frisket off the roll and onto your mold. You can then reposition it as needed. Frisket does not leave an adhesive residue. When trimming it out, make sure to use a new blade in your x-Acto knife and if you notice a “pull” or once the blade starts to hang, change out the blade to a new one.
KFFP requires a long shake time. Do it, it’s tedious..I wear a watch. Following the manufacturer’s directions insures that the paint goes on smooth, as intended, and the color saturation is correct. If you reduce the shake time, you may discover that the color is uneven, the nozzle may spit or clog, or you may just blow out the propellant.
One of the tricks I use before I start painting, is to immerse the can of spray paint into a warm water bath for a few minutes. Sounds strange, but the paint goes on beautifully from being slightly heated. You don’t have to do this, you can apply it without heating but I have found that the paint flows better.
KFFP will dry “to the touch” in 15 minutes according to the product label. But air temperature and the amount of humidity does make a difference in the drying time. It can be greater than 15 minutes. To check for dryness, touch an area at the back of the mold or bottom. A fingerprint in either of those areas won’t show—much. In this example, I sprayed one light coat on the front of the candle. I grabbed the top of the candle immediately after spraying the front, rotated it, continued around the side, rotated the candle to the back, and again for the other side. When doing a candle or other circular blow mold, you don’t want to overlap where you have already painted. As you come full circle, nearing the starting area, sweep the can away from the blow mold’s surface and off. You will have a seamless and even paint job.
Make sure your first paint color is completely dry before moving on to the next color or before applying a second coat. I will often wait until the next day to allow for a complete curing time. With KFFP, although it does dry quickly, it has not completely bonded to the plastic in 15 minutes. Waiting to switch colors, which often means having to mask over a recently painted area, reduces the chances of any of the new paint coming away when you pull the mask off. In my experience, I simply will not rush the drying time, it could mean all that work being ruined. Once dry, you can then apply a second coat if needed. Fortunately, a second coat is rarely required with any of the darker hues.
Some tips when using spray paint.
Try to remember these three key points when spray painting: angle, rate of speed, and keeping your distance. To paint, direct the can away from your blow mold. Depress the button, start the spray and then commence sweeping the paint across the mold and just beyond it. At that point, immediately lift your finger off the button and stop. Use a steady stroke. Start again using the same technique. If you have the can aimed directly at the mold and you’re too close when you start, more than likely, you’ll be creating a splotch, an effect which is difficult, if not impossible, to even out. As you develop a feel for spray painting, you will not need to stop and will be able to continue sweeping the can lightly across the surface in an arc. Although spray paint is designed to be easy to use, getting an excellent result does require practice. Always remember to depress the button and keep it depressed for the entire sweep. Do not punch the button, don’t start, stop, start, stop. That will cause blotches, the paint will be uneven, you’ll get drips, and you will not be happy with the final product. Use a steady side to side sweeping motion. If you have elevated the mold on a table or work bench, step back, hold the can at least 6 inches from the surface of the mold at about 90 degrees. Keep the speed of your sweeps the same. Do not race across the surface, but going slow is not desired either.
The slower your pass is across the surface, the thicker the paint will go on. You want to apply a thin even coat of coverage. To achieve this, you need to move the paint fairly quickly and move each sweep at the same rate of speed.
Ideally, have the blow mold lit when you paint. You can then see coverage and if you will need another coat. If you have never painted with spray paint, practice with it before you decide to repaint your blow mold. Use a clean empty milk jug with a light cord in it for practice. You’ll be able to get the technique down before you start.
Additionally, the nozzle can be oriented to horizontal or vertical. Generally, leave the nozzle in the position it came in. Orienting the nozzle to vertical creates a thin vertical spray pattern. As you develop your skills, you will find this comes in handy from time to time.
Once you’re sure the paint is completely dry you can do a second coat if needed.
To do your second color, you now have to expose the previously taped over areas and cover the surrounding areas. In the case of the candles, I left the tape on the white spiral, wax drips and only needed to cover the red area surrounding the pine cones and Holly. I used a large garbage bag over the candle and cut through to expose these areas. I butt the tape carefully so that the least amount of new paint would be affected. By doing it this way, there is little chance of pulling off the new paint. I also applied small pieces of tape to the individual red berries. I then painted the pine cones green. If you know that you will not be going near an area that is already painted and you are confident in your skill with spray paint, you can skip covering some areas. This is a judgment call on your part, but keep in mind that if you are outside in a breezy location, no matter how good you are with that spray can, the wind is going to cause overspray.
Removing the tape is simple but there is also a correct way to do it. Resist the urge to pull the tape straight up and off. Chances are high that if you do, you will pull paint off. Why is that? Because there is now a paint seal over the surface you just painted. This seal covers not only the mold but the tape as well. You want to cut through that seal as you pull the tape off. Work a nail under the edge of the tape so you can grab it. Pull it up slightly and then straight back over itself, keeping the tape you’re pulling back low over the tape that is still adhered. This causes the tape to cut through the paint seal. You will end up with a crisp, clean, line of paint rather than a jagged line where small bits of paint are pulled away.
If I had wanted to paint these candles using three colors, the spiral for instance, I would have used a large garbage bag, cut it to reveal only the spiral running around the candle, taped it off, and painted. This is the method I use when going with 3 or more colors.
Matching the original color of a blow mold, as delivered by the factory, is often impossible to achieve with spray paint. I use various brands in order to increase the color palette available. You’re cautioned that if you use two different brands of paint and intend to clear coat or use a UV protective finish, you may encounter compatibility problems. I try to use the same brand of paint with the same brand of clear coat.
My first choice when it comes to paint is KFFP. Krylon offers a larger color palette at this time than any others I have found. KFFP sells for approximately $6 for a 12 oz can. It can be purchased at Ace, Do It Best, TruValue Hardwares, WalMart, Kmart, some Sears stores as well as on line.
The most common question I’m asked “what color do you use for flesh tones?” Currently, there is only one color available that works for a Caucasian flesh tone, it’s called Buttercream. The Krylon color chart can be found here: <http://www.krylon.com/products/fusion_for_plastic/
RustOleum also makes a good product. RustOleum’s available color choices are more limited, but do offer a few different colors than KFFP. In my experience using RustOleum, I have found that it does not adhere as well as KFFP, but it does work satisfactorily. This paint is available at Home Depot for approximately $6 per 12 oz can. The RustOleum color chart can be found here: http://www.rustoleum.com/cbgproduct.asp?pid=118
Valspar, widely available at Lowes and Michaels, is yet another choice. I wasn’t impressed with it. I found it to be thin and it did drip. You may have a different experience. Valspar sells for approximately $5 for a 12 oz can. The Valspar color chart can be found here: http://www.valsparspray.com/Product/pcode---6791
All of these brands are specifically formulated to adhere to the slick surface of plastic. You do not have to sand or rough up the surface when using them. On only one occasion, I lightly sanded a particularly slick blow mold, a heavy Bel Aire Plastic Santa Claus. I used 600 grit sandpaper on a block, sanded it wet, in a light circular motion. Otherwise, I’ve found sanding not necessary.
You may be tempted to buy the plastic primers that are available. There is no need and I don’t recommend it. Repainting a faded plastic deck chair that is going to see use and wear is very different from repainting a blow mold. Priming creates another layer of paint over the surface of the plastic. Primers help to insure that the paint will stay on that deck chair. But the more paint on a blow mold, the thicker the layer, which reduces the amount of light that will shine through.
I have tried many types of spray paint over the years. If you paint the blow mold while it is lit, you will see the variation in coverage afforded by different brands of general purpose spray paint.
Dupli-color acrylic and enamel spray paints are designed for general purpose use and some are made specifically for use on vehicles. They are dense and even when used with a very light hand, I found them to retard too much light. I advise you to steer clear of them even though they say “general use”.
Testors has a very large line of enamels and lacquer spray paints. Their color palette is very in depth, making them tempting. I found that if sprayed on very lightly, the paints adhere well and don’t restrict too much light. These paints are mostly used by model makers so they are denser and you need to use an extremely light touch when spraying. The draw back to Testors is that they are expensive. A 3 oz can sells for approximately $5 to $6.
Clear Coating/UV Protectants
Whether or not you wish to clear coat is up to you and where you live. In the southern U.S., where sun and heat is an issue, I definitely urge you to clear coat your newly painted blow molds. There are two major problems I have seen in blow molds I’ve purchased from southern states; terribly faded paint and brittleness. Many weeks of constant exposure to the sun, over just a few years, does more damage to blow molds than the weak sunlight we receive in the north. Even though I live in the north, I have adopted the practice of clear coating most of my restorations, especially when the paint job was complex and time consuming. I do not want to have to repaint the mold again and will do what I can to insure the paint job will last as long as possible. But I have many molds that I have repainted where I did not do so. It’s entirely up to you.
There are different products available, more than I have outlined here. But the two I’ve been very happy with are by Krylon and RustOleum. Be aware when using either product, you must apply them either outdoors or in an extremely well ventilated area. Both products contain acetone and toluene and are highly toxic when inhaled. Trust me, you do not want to breathe either of these.
Krylon UV Resitant Clear is an excellent product. It’s also widely available at the stores previously listed. It does not yellow and produces a hard, chip and fade resistant surface. It’s available in matte as well as a gloss finish. An 11 oz can sells for approximately $6 to $7.
RustOleum Painters Touch is also an excellent clear coat and is an UV inhibitor. Like the Krylon product, it produces a durable finish, it’s available in gloss, semi-gloss or matte. A 12 oz can sells for approximately $4 - $5, making it an excellent value.
I use no less than two light coats, no matter which product I use. It’s applied the same way you use regular spray paint and wait for it to dry between coats. Deciding how much you will need depends on the size of your blow mold. The Christ child below used approximately half a can of matte finish.
Any questions? You can reach me in the HU blow mold forum. Happy molding!
Last Updated (Sunday, 25 September 2011 20:37)