ThermaTru Doors

Frequently Asked Questions

If you don't find an answer to your specific question, call us toll-free at 1-800-THERMATRU.


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Can the top coat be diluted to spray on the doors? Diluting the top coat is not recommended. The top coat can be spray-applied as formulated.

Is the temperature extremely important? Yes, the temperature is extremely important or else the stain will flake, fade, and have a milky look. Temperature should be between 50 and 90 degrees Fahrenheit and the humidity should be below 80%.

What if the weather is not accommodating to finish the unit, how do I protect the jambs and door? Within 2 weeks you can prime or clear topcoat all unfinished wood components until your weather is more accommodating.

What is the time period I have to work in to “easily” remove the stain, lighten the stain or darken the stain? Within the first 24 to 48 hours you can lighten the stain color with the brush or remove with mineral spirits. After 48 hours you will need to follow the Stripping to Refinish instructions.

What are the time periods to leave the stain on the door for lite, medium or dark color? Lite is 5 minutes, Medium 7 minutes, and 10 minutes for dark color.

Can I use lacquer thinner? No.

Do I sand the door before staining or before applying a second coat of topcoat? No, this is not recommend or necessary for the topcoat to adhere.

Can the topcoat be sprayed? Yes, the finishing instructions covers this application.

How do I stain the clear jambs? By following the Staining The Components of the finishing instructions

Why can’t we put the video in the kit like Anderson and Pella do? Our finishing video can be viewed on our website .

Do "quick dry" paints work on fiberglass doors? Quick dry paints often have fast evaporating solvents like acetone (finger nail polish remover) and some slower evaporating solvents. Cases are known where overspray from an interior fast dry paint was over painted before the slower evaporating solvents had flashed off. The result was blistered paint.

What happens when topcoat and stain is applied and it stays 50F for only a few hours before cooling significantly? The topcoat will sometimes whiten in areas. Graining appears to be more susceptible. It is probably because the temperature went below the minimum film-forming temperature of the topcoat before the film was well built, trapping water, and disrupting the film build. Solution: If small, dub some stain and wait until spring to truly finish. If generally milky, wait until spring, then strip and refinish.

What is Therma-Tru's steel door primer? Therma-Tru's steel door primer is a water-based acrylic latex. The primer is baked-on at the manufacturing plant. A variation of it is available for spray-on touch-ups. The formulation is different because of having to cure at room temperature and having to be miscible with the propellant.

What is the 'white powder' that has appeared on my door stained with a Therma-Tru finishing kit? We see this when the stainer has applied Therma-Tru stains very heavily (usually to achieve a dark color). There are UV inhibitors in the stain, which will migrate through the topcoat when there is a lot of stain on the door. Wash it off with detergent and water. It may come back one or two more times, but will eventually cease. To prevent in the future, use less stain. Most doors do not require heavy stain coats to achieve dark colors. Reducing the UV inhibitor will in the stain will begin reducing the durability of the finishing system.

Can automotive body paints be applied to Therma-Tru steel doors? No. The "hot" solvents and "drying" solvents will, in general, attack the primer on the steel door surface.

How uniform is the color of a Premium steel door? The Premium steel door (and Construction Series) are primer coats and therefore may vary slightly in color between batches. These variations will not affect the final paint color of the finish coat.

What paints can be used on a Smooth-Star without priming? Therma-Tru has tested many brands of paint, but not all. Below are some we can recommend highly: Sherwin-Williams Exterior Satin Latex (A-100 Exterior) Pratt & Lambert Accolade Eggshell Premium Exterior Acrylic Olympic Overcoat Satin Latex Porter Acri-Shield Premium Acrylic Latex Porter Advantage 900 Exterior/Interior 100% Acrylic Latex Benjamin-Moore MooreGlo Exterior Latex Sears Weatherbeater Exterior Acrylic Latex Satin and Semi-Gloss Mautz Exterior Acrylic Latex Satin Pittsburgh Paints Manor Hall Exterior Premium Eggshell Be watchful of paints with major ingredients like "vinyl polymers" or "polyvinyl acetate" or that are labeled "interior/exterior". In many cases they appear not to adhere well to Smooth-Star.

Does Sherwin-Williams' Super-Paint work on Smooth-Star doors? (Super Paint) Super-Paint is a sprayable variation of Sherwin-Williams' A-100 paint. We use it on some of our displays. Super-Paint should be used cautiously. Our laboratory results show that the application is sensitive to environment conditions (temperature, humidity, etc.) during the painting process.

How can I get free finishing instructions for Classic-Craft or Fiber-Classic doors? Visit the online printable instructions here

Can I order prefinished doors? Ask your dealer for more information on the prefinished styles that are available through their distributors.

How do I obtain stain? Stain can be bought through your local Therma-Tru dealer, by calling 1-877-99-STAIN, or online by placing an order on our website. You can also purchase just a can of stain or a can of topcoat from the toll free number, 1-877-99-STAIN.

Do I have to take the door off its hinges before finishing? No. The weatherstripping can be pulled out of the jambs, so it can be closed and locked during the drying period. Weatherstripping can be pushed back into the jambs after topcoat has dried.

How much will one kit do? A single door unit with sidelites, a double door unit or an 8' door unit, inside and out.

What does the Therma-Tru stain kit include? Everything you need to clean, stain and topcoat your door. Mineral spirits, stain, topcoat, brush, rags, gloves, stir sticks and two skin samples.

What do I use to clean the door with? Using a clean, dry rag, clean the entire surface with either the provided mineral spirits or an all-purpose cleaner such as Top Job, Mr. Clean or Pine Sol. Rinse soap off thoroughly. Allow to dry completely.

Which Therma-Tru doors can be stained? Classic-Craft and Fiber-Classic doors.

What stain/paint should be used on Therma-Tru Classic-Craft or Fiber-Classic fiberglass doors? To stain, we only recommend the Therma-Tru finishing system. The doors can be primed and painted with a high quality acrylic latex, alkyd oil or solvent oil-based primer and paint.

Do I have to prime Classic-Craft or Fiber-Classic doors before staining? No. Priming is not necessary or recommended unless you are painting your door. For best adhesion, we recommend priming the door with an alkyd-based or acrylic-based primer before painting.

My wood jambs are clear and I want to stain them. Do I do anything different? You should purchase a can of “wood sealer” and apply it to the jambs to limit the penetration of the stain or you can wipe the jambs down with mineral spirits before applying the stain. The stain is a heavily pigmented stain and could stain the jambs darker if you do not apply a sealer or use the mineral spirits first.

The wood jambs are darker than the door, how can I make them the same shade? You can put a thin layer of the topcoat on the jambs so the wood will not absorb the stain as fast, or wipe the jambs with mineral spirits.

What if I don't like how the stain looks and I just finished it? What can I do? If you have just finished staining and it is too dark or you want to start over, then use mineral spirits. Use a rag and wipe the stain off. Or if you just want to lighten it a little, then use your brush with mineral spirits on the tips and lightly brush the stain and wipe the excess onto a clean rag.

Why do I have light and dark areas? Perhaps too much pressure was applied with the brush while feathering. Go back and apply more stain to the lighter areas, wait a little bit, and then feather lightly. Remember to lightly brush completely through the section being stained.

Can I apply a second coat of stain to make it look darker? Yes, but wait until the first coat is dry (48 hours).

Can I mix stain colors? Yes, as long as you are mixing Therma-Tru stain with Therma-Tru stain. The stain can be tinted with any "universal" tint to achieve a certain color.

How long does it take the stain to dry? At least 48 hours. It is best to do the "skin" sample test, as instructed. It must be completely dry before applying the topcoat. (See finishing instructions).

How do I clean the brush? After staining, use the mineral spirits. After top coating, use soap and water.

Why does my door look "milky" in some areas? This can happen when the topcoat is applied too heavily or too close to dusk Sometimes this happens in the corners of panels, because of a drip or run. You can dab on a little more stain over the milky area by using a cotton swab or an artist brush. Let dry 48 hours, and then reapply a light coat of topcoat over the restained area, again, using a cotton swab or a small brush of 1" or less in width. Blend in topcoat layers as needed, but do not over brush.

How long does it take the topcoat to dry? 3-4 hours. It takes a least one-week to totally cure, but it is dry to the touch in 3-4 hours.

How can I get a "high" gloss finish? You can apply 3-5 coats of the Therma-Tru topcoat to achieve a “high” gloss finish. Let each layer dry 4 hours before applying the next layer.

Should I apply a coat of wax over the topcoat? No, because it already contains some wax and silicone in the formulation. Water will bead up on it and run off.

How do I maintain the topcoat? Before the topcoat fails, reapply a fresh coat of the topcoat. When you notice the topcoat beginning to fade or lose its gloss, then clean the door with either mineral spirits or an all-purpose cleaner, rinse and let dry. Then reapply one very thin coat of the topcoat to all surfaces of the door.

How do I remove the stain and topcoat? As instructed in the finishing instructions.

What paint should I use on the Classic-Craft or Fiber-Classic door? These doors should be primed and painted with a high quality acrylic, alkyd or oil-based exterior house paint. Primer and paint should be produced by the same manufacturer and be made to work together. Paint all exposed sides, edges and ends of the door.

Can I stain my Smooth-Star door? No, it is a "paint-grade plus" door and can only be painted. After cleaning, paint with a high quality exterior grade latex or acrylic house paint.

Do I have to prime my Smooth-Star door? No, it is not necessary to prime the door, but if your door has a doorlite in it, then the molding around the glass should be primed with an acrylic or alkyd primer. Wipe the frame with a clean cloth first. Then prime and paint.

How do I repair nicks and scratches or scuffs in the stained finish on my door? Clean area first with mineral spirits or an all-purpose cleaner. Then, use a small artist brush or cotton swab to apply stain to the nicks or scratches. Carefully wipe or brush off excess stain, let dry and then apply a thin coat of the topcoat over the repaired area. Refer to the finishing instructions under "Repairs". Also, there are a variety of “touch-up markers” or repair pencils that repair scratches or nicks in finishes on fine wood furniture. These do a nice job too.

How do I strip a fiberglass door to restain/repaint it? To strip a fiberglass door, you'll want to use a methylene chloride-based stripper. We recommend Dad's Easy Strip, Big Tough, or Bix Stripper. Follow the directions on the product purchased. Use a brass wire brush, a medium hard nylon bristle brush, or grade 000 or 0000 steel wool to remove the residue. Do not leave stripper on raised moldings or panels any longer than 2-3 minutes. (Please refer to the Therma-Tru finishing instructions.) Paints, stains or topcoats can be removed this way.

Stripper says to not use it on fiberglass. Why do you say it is okay? Fiberglass doors manufactured by Therma-Tru are made from a fiberglass material that you can safely use the recommended strippers on. Again, follow our finishing instructions for stripping. It mentions it is okay to use strippers on Therma-Tru’s Classic-Craft and Fiber-Classic doors.

Does the kit contain strippers? No. Stripping materials have to be purchased separately.

Do you have a kit for refinishing, containing strippers and brushes? No. Stripping materials have to be purchased separately. Purchase these materials from hardware, paint or department stores.

Can I shut my door if the stain is still wet? The weather-stripping can be pulled out of the jambs, so it can be closed and locked during the drying period. Weather-stripping can be pushed back into the jambs after topcoat has dried and cured.

How do I clean the glazing from around doorlite frame? Remove any excess glazing sealant by first spraying with a window cleaner, rubbing alcohol or water. Use a single edge razor blade or clean putty knife to score the glazing along the edge of the frame. Holding the razor blade or putty knife at 45-degree angle, scrape glazing from the glass. Wipe remaining residue off with window cleaner or mineral spirits. Clean the frame with mineral spirits or mild detergent and water. Rinse well and allow to dry completely.

Can the Therma-Tru topcoat be sprayed on? Please refer to the Therma-Tru finishing instructions for topcoat application producers.

What can be done if I have a scratch on my wood-grained Therma-Tru door? Please refer to the Therma-Tru finishing instructions for repair options.

What stain colors does Therma-Tru offer? The Therma-Tru stain colors can be viewed by clicking here.

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