Seam Sealer Quick Tips


There are many different seam sealers out there and that alone causes a bit of confusion. We’ve been asked about what seam sealer we use, so it sounded like a good idea to briefly go over how we do it so that other’s questions might be answered. Now keep in mind, there are many correct approaches, so ours may not be any better than the next, but it has worked well for us. To begin, we seam seal just before the application of the color coat. Some seam sealers do require that you apply them to certain substrates, so you’ll need to check the one you plan to use. 


We like the LORD Fusor 800DTM sealer. It is able to be applied to bare metal as well as over primers , so it’s pretty versatile. Keep in mind the intent of seam sealer is to keep water from entering cracks and crevices in body seams. That said, it shouldn’t be used to bridge big gaps of improperly fitted panels. Before we apply the seam sealer we blow all areas out to rid the lose debris and then we use the LORD Fusor 703 prep/adhesion cleaner. Some people use dewax / degreaser, but we like to stick with a system specified by the seam sealer manufacturer. With the areas wiped down and dried, you break out the caulk gun and start lying down a bead of sealer.


Generally less is better than more and the best tool to use to spread / smooth the seam is a finger (gloved) dipped in gun wash solvent. This provides a clean, smooth joint with minimal sticking to your finger. Try to do only manageable areas so that you minimize the “skinning” that occurs (as it should) of the sealer – we do about 4 feet at a time. This seam sealer can also be brushed once applied (the top cowl area is a good example of this). Use an acid brush dipped in solvent and your results can look much like a factory joint. 


One other tip – get yourself a “Heavy Duty” caulk gun from Home Depot – they aren’t expensive ($14.98) and it is a 160:20 leverage gun so it will also handle very viscous Urethanes used for setting your glass. How much sealer do you need to buy for your job? Well, for the El Camino shown it took slightly less than 2 tubes to do the entire vehicle. For the most part the biggest challenge to seam sealing is making sure you got every seam sealed before you paint, because fixing it after the fact isn’t much fun!