We join building engineer Ross Trethewey on a road trip as he heads to Miami to help a homeowner troubleshoot his HVAC system. With the help of a local pro, Ross performs a visual inspection, assesses the system’s airflow, and performs leak tests to determine the issue before giving the homeowner some tips toward a solution.
Next, we meet Shelby Barnhart, a metal fabricator from Northern Connecticut. Shelby’s career in metalworking started as a teen in her high school’s metal shop and during her summers working under an experienced metalworker. After high school, she began learning the artistic side of metalworking before starting her own handrail-to-order business in the barn her father built in 1993. She tells us all about her stories and experiences in this contractor highlight series.
Finally, we tag along with paint expert Mauro Henrique as he helps a pair of homeowners solve their shellac issue. After assessing the issue, Mauro shows the homeowners how to soften the shellac and remove it from the woodwork before refinishing it with a polyurethane finish.
How Experts Troubleshoot an AC System
Heating, ventilation and air conditioning (HVAC) systems can be complex and mysterious to homeowners. So when there’s an issue, finding the cause is often way beyond the DIYer’s scope. When a Miami homeowner was tired of living with temperature imbalances throughout his home, he called the team at Ask This Old House for help, and building engineer Ross Trethewey showed up to help.
Where to find it?
Assistance provided by: Comfort Dynamic, Inc.
Celebrating Craftsmanship | Shelby Barnhart
Today, we highlight metalworker Shelby Barnhart and her journey in the metalworking trade. She tells us about her time as an apprentice, when she learned modern blacksmithing techniques, and how she runs her business today.
Where to find it?
Shelby Barnhart’s company: Arc and Hammer.
How to Remove Shellac from Wood
Shellac was a popular finish many years ago, but it has its challenges. It needs to be applied in the right temperatures, and its drying time needs to be respected to prevent uneven textures. But, shellac is tough and can take forever to sand. When a pair of homeowners needed their woodwork repaired, paint expert Mauro Henrique knew just what to do.
Where to find it?
Mauro prepped the area by covering the floor with drop cloths and protecting the windows and surrounding walls with Scotch Blue pre-taped painter’s plastic sheeting and painter’s tape.
Mauro removed the shellac by applying denatured alcohol–any type will work. He poured the alcohol into a plastic bowl and used 2-½” to 3” flat chip brushes and then had it sit for a couple of minutes before scraping it off.
To scrape the shellac—wear safety glasses, an n95 mask, and disposable gloves.
To scrape off the first, thick layer of shellac, Mauro used a mix of his Warner carbide paint scraper, painter’s multi-tool, 1” to 1-½” putty knives, and a 5-gallon bucket to catch all debris.
After the thickest layer was off, fine grade (#00) and medium (#1) steel wool pads and heavy-duty scour pads were used. Scour pads and a painter’s multi-tool are helpful for grooved areas. Multi-purpose shop rags were used to wipe tools clean of the shellac in between scrapes.
Before adding the new finish, sand the trim with 220-grit sanding sponges and pads. Use a shop vacuum to vacuum up all debris.
Mauro used Varathane Clear Satin Water-Based Polyurethane. He chose a water-based polyurethane to avoid excessive off-gassing because of the young child in the house. Oil-based polyurethane has a much stronger odor, although fewer coats would be needed. The water-based polyurethane will need 2-3 coats, maybe more depending on the wood. Drying instructions will depend on the manufacturer but water-based will dry faster than oil. 2-½” to 3” synthetic brushes were used.
Original Air Date: May 8, 2025, Season 23; Ep. 23 23:42
Products and services from this episode
- Special HVAC assistance: Comfort Dynamic, Inc.
- Shelby Barnhart’s company: Arc and Hammer
- Paint scraper manufacturer: Warner
- Stain manufacturer: Varathane
