Does anyone have any insight on spraying epoxy? Even with Additive F I’m still getting a few brush marks and would be interested in trying to spray my mix but it’s too thick. Is there anything I might add that would thin it out without changing its chemical makeup too much?
Thanks
Hey fergusre,
we thin them out by using slightly heated epoxy, adding alcohol, and using a spreader first and finishing with a brush. Brush type and techniques are HUGE factors to getting no brush marks. We can get a mirror-like finish using the spreader/brush. HVLP equipment may allow spraying but I would be wary of the costs in the form of overspray.
Whare are you using to heat the epoxy? are you heating it already mixed with hardener?
We’ve been using a microwave to heat the resin component for the last several years. Not too much time, usually about 10 or so seconds depending upon the power rating of the oven…
Resin Research sells an “epoxy modifier” which is called “epoxy thinner”. It’s a special formulation of alcohol precisely suited to accomplish the goal of spraying it.
Using a HVLP (High Volume Low Pressure) spray gun, or, in some cases even an airbrush [such as the “Iwata” brand] will allow you to eliminate much over spray. Regardless of over spray… you will save a lot of time by spraying those final topcoats & create an excellent appearance with no brush strokes- as well as create a more even layer of epoxy. Brush strokes [at the micron level] are not as ideal as an atomized finish which can easily have inconsistencies in thickness.
Anyways, after all time is money. Also, quality product makes money so between those 2 additional benefits I’m sure you will realize there is some reasonable level of justification towards any miniscule quantity of over spray. If you can make topcoats faster, cleaner & more even but spend a little extra in over spray then what the heck- it’s worth it, no?
I appreciate everyone’s input. When you’re talking about a HVLP spray gun are we talking about a compressor sprayer or a piston driven sprayer like a Wagner power sprayer? I’ve used the Wagner extensively painting houses and the overspray is unbelievable. It’s mostly due to the fact that the Wagner product is not that great. However, I would consider using it for the finish coat as you mentioned. Please excuse my ignorance as I’m new at this but highly enthusiastic when it comes to epoxy boards. My brother-in-law and I finished our first board together (7’2" squash tail) and it came out extremely well. He claims it rides as good, if not better, than our other store-bought boards. There may be some pride issues involved but we’re a little biased because it was made with our own hands. I can’t wait to see how the long boards come out with your suggestions.
Spraying epoxy is very dangerous.(not talking out epoxy base paints here) I have only seen it done with those full on bee keeper suits with hood respirators. I have never seen a non paint epoxy product ever recommended for spray. If you did it you need a paint booth. Even though you have heard all the talk of the low VOC’s of epoxy and respirators are pretty much abadoned when using these products, spraying aerosolizes the epoxy and is super dangerous without the proper equipment.
Write Greg L from RR and ask him.
Sound advice! I hadn’t even considered the effect that atomized epoxy would have on unprotected lungs. If it got in your eyes the damage might also be irreparable. I’ll take all of this into consideration before proceeding. Thanks.
Spraying “any” type of product whether dangerous or not should generally be done in a spray booth using protective clothing, etc. However due to time factor, & assumption you understood basic protection, I did not get into an extensive length about protective gear. I was focused on the specific technique as a result of a very specific question of spraying epoxy… not the protective equipment used… which would be a whole other topic completely.
I did refer to Iwata spray guns/airbrushes. Their site is www.Iwata-airbrush.com (I do not work for them nor am I paid to endorse that product- I’m an independent distributor in the Caribbean). Most spray guns require compressors; I would never use a Wagner to spray anything but my house, & even then I would wear a respirator, eye protection, clothing protection, etc.
Greg knows his stuff but he is busy these days. If it makes is easier for you, simply go ask any paint supplier, professional body shop or even an airbrush artist (preferably all three) about protective clothing & what to do when spraying certain types of chemicals. To protect everyone you should always spray paint & chemicals inside a spray booth using protective clothing. A Spray booth can be bought or built using a number of methods & protective gear bought from a number of places but I’m not at liberty to advise you on all the details in just a couple of paragraphs. I hope this helps answer your specific questions… & yes, if you can then ask Greg. He would not be a guy to lead you in the wrong direction regarding these matters.
Be smart, always get advice from several sources & always protect yourself & the environment the best you can.
Enjoy surfing & building boards… but be very careful how you make them & the products you use in the process. There’s a repercussion to everything you do.
Thanks for the more in-depth explanation. I did a little research and found quite a few sprayers that would work, but after all the precautions required to set up a spray booth I may reconsider my approach to applying epoxy. I also have neither the experience nor the confidence in this type of application without significant money going out the door. I haven’t had the opportunity to try heating the epoxy as mentioned before so I might give that a shot. I appreciate everyone’s input and experience because I certainly wouldn’t want to re-invent the wheel, so to speak.
Hey fergusre;
What PlusOne said above is good advice as an alternative to spraying. Thinning out the resin by slightly heating the epoxy (the resin without additives or hardener) then adding thinner/hardener &/or additive after it’s warm… and then using a spreader (a plastic squeegee-like tool) & a wide, but clean brush is a good option as long as you can use them correctly.
However you may discover (especially in warm countries) that your brushing technique [without heating] can be good enough alone to eliminate brush strokes. You also may be brushing out too thin or too late in the curing process, which may be your only problem at this point –but heating the resin certainly can help & you should try various options.
Overall, your brush type and technique is one of the most important factors that will eliminate brush marks. You actually can get a great finish using the spreader/brush system but you must have a very good technique to accomplish this so practice it a lot & let us know what you come up with OK!
Hey fergusre,
I am assuming a “finish coat” here rather than a hotcoat or filler. If you sand the board properly, you can get really good results with this approach. One thing I wanted to add to the tips is to be sure you have a good working environment. During the time that your epoxy is going past “B stage” it is strongly advised to have the room at a minimum of 75 F. Also, clean and dust-free with still air. I have to use a heater in southern California (right now).
The most important tips at this point would be your brush and technique. The brushes are usually “throw away” types when using epoxy. I have to admit, that’s good sense. Getting to the higher level of finishes will require using a brush that will cost $10 to $25. Nobody likes this, but saving a quality bristle brush requires the use of acetone. The brushes I really like are made by Purdy and are 4 inches wide. I cut the handles down. These are available at most major “home improvement” centers.
Technique is everything. Assuming you have your epoxy thinned and ready and your board is beautifully sanded (I like a final skim of 220 grit), here’s a valuable tip. We call the brush pattern the “diamond stroke”. It is used in quality old furniture building and was used in early automobiles; yes, cars, like the Model-T with perfect results.
Most of the brush strokes described are just to set up for the final brushing. Look at the “set up steps” as arranging your material in the desired thickness and eveness. This should be in your head as you work…
Pour the entire bucket down the middle of the board. We use spreaders, but your brush will do if the epoxy is thin enough. Cut ‘the pour’ in half, down the stringer, using the brush edge-wise. Go quickly row-by-row and get the board covered. Let it flow out for almost a minute. Now brush kinda rail-to-rail BUT at a 45 degree angle, you know, like a candy cane. Each stroke should overlap (common sense). Let this flow out for about a minute. IMPORTANT: Now, brush rail-to-rail at 45 degrees BUT the opposite of the previous 45 (90 degrees is “opposite”). Wait about a minute; it seems quite long but wait. Finally, do lengthwise strokes first down the stringer and out to the rail closest to you, then repeat on the other side. Be very aware of your brush pressure. Your walking style will affect the brush pressure, that’s the level you should be at…
The SECRET here is the speed your brush travels down the board. Too slow and the brush will remove too much resin and leave GROOVES in the coat. Too fast and you will get a lumped finish, like cottage cheese, and this won’t flow out too well. Your body motions should be very fluid as well (SERIOUSLY) and you will be amazed at your results. A really good brush is easy to read.
Lastly, try not to repeat a sequence or “back up” a step; that will be the skill you will be working on after knowing the above info…
Hope this helps,
PlusOneShaper and 12 Reasons,
I intend to try all of the above. I am currently working on two 6 foot boards that I’m making for my kids and will be putting on the gloss coat next. Today (1/2/2006) would have been the perfect day to work on the boards but I was spending time at the beach away from the shop (the temp was 85, another brutal winter here in South Texas). If this keeps up, I should have some great working conditions. However, as a precaution, we’ve put together a hot box with space heaters because the weather can change at a moments notice. I am very interested in trying the brush technique as my previous technique of haphazardly spreading the epoxy on the board has resulted in some pits and thin spots, especially around the fin boxes (future fins). I’m glad you clarified the process of heating the epoxy prior to the mix because I was planning on heating the final mix. I can see the wisdom in heating prior to the mix as the hardener wouldn’t need any help especially if it’s a fast hardener.
I’ll let you know the results as soon as I can.
Thanks for the help and Happy New Year.