I’ve always said, it’s not the elephants that’ll kill you, it’s the mosquitoes. The little things that quietly sneak up on your finish, that you don’t realize until it’s too late. We all focus heavily on spraying technique as paramount to achieving high level sprayed finishes. While technique is important, product control begins before you even pull the trigger. Here are a couple of tips to help eliminate product based variables.
This is about product handling. Sometimes, finishers take for granted what the product itself needs in order to be happy in the process. Product happiness directly relates to spray gun happiness, which transfers right to the finish you lay down. If the product and gun are happy, and your technique is good, the finish should be a thing of beauty.
Tip 1: Strain Product: Always
Straining is a topic that we talk a lot about in our Prep to Finish paint training program (preptofinish.com). Conventional wisdom and common sense dictate that straining is a great way to remove contaminants from product while it is still in liquid form. This is certainly true, but there are other, more subtle considerations that make straining a good idea.
Specifically, building the habit of straining ALL product every time you load your cup gun is cheap insurance at a deeper level. As the product world transitions more into waterborne platforms, the practice of shaking a can of product is not recommended. Shaking a waterborne tends to bubble it up right in the can, and even after the bubbles appear to have settled out, they often still transfer through the gun and into the finish.
This makes sense, because even in a low pressure system, there is still pressure and force driving the liquid through the needle. You may not be able to see large bubbles in the cup, but there can easily still be tiny ones inside the liquid form product, that will pass through your gun tip, and lay down with the finish as micro bubbles. This creates backwards motion, because usually we will have to sand the dried micro bubbles smooth to remove the nubs, and do another round of spraying.
I recommend a soft stir and then a full strain of all new product. Using a fine mesh cone style strainer, the product actually gets a “combed” effect through the strainer, so that it enters your cup with ideal consistency and viscosity.
Lately, we have rediscovered the convenience of using a filter stand when preparing product for HVLP spraying. If you don’t have a strainer stand, I highly recommend that you pick one up, as it makes it easier and more convenient to ritualize the straining habit. You don’t have to stand there and hold the cup and can. You can be finalizing your tack wipe on the piece to be sprayed, so there is a bonus efficiency gain through this simple implementation. Simple multi-tasking at its best.
Tip 2: Never Spray Outside. Ever.
Another concept we drill in finish training is controlling the environment in which spraying occurs. It always amazes me how many finishers tell me that they prefer to spray outside, because it is just easier than creating clean, controlled conditions in the workshop.
While this may seem convenient to you as the technician, it is not at all appreciated by your spray gun, or the product being sprayed.
Aside from the obvious risks of contaminants and unpredictable lay down of product, the primary problem with outdoor spraying is the unpredictability of wind. The slightest random breeze outdoors will wreak havoc on the transfer efficiency of your gun. In other words, you are shooting at your target, and wind is passing through the surface area, moving and diffusing your sprayed fan.
Remember, HVLP spraying is low pressure. The sprayed fan is very fine, which is the benefit of HVLP spraying to begin with. Because of product loss in the air, outdoor spraying often requires 4-5 coats to achieve the level of finish that can easily be laid down in 2-3 coats in the controlled environment of the workshop.
The wasted product is a big deal, because fine finishing products are often pricy. Why spend twice as much on materials? Further, the time that it takes to create additional finishes due to loss of transfer efficiency puts projects behind schedule. Whether you are a hobbyist or a pro finisher, time is just too precious to waste.
So, with spring coming, rather than embracing the nice weather for outdoor spraying, open up the windows in the workshop and give it a good spring clean and organize. Set up a dedicated spray area that you can control, both in terms of cleanliness and air flow (a simple exhaust fan out a window). The best way to exhaust is to be drawing air away from the finish area, not randomly into it or through it.
These two simple adjustments – straining habits and controlled environment – will make a profound difference in your finished results, while saving you time and money. It’s all about quality and efficiency.
Happy spring and happy spraying!