leehljp
Member Liaison
This is a thread that I looked up because of questions on another thread by
Fine Engineer-Jeff. "Oak with Oil Based Stain and CA Finish'
https://www.penturners.org/threads/oak-with-oil-based-stain-and-ca-finish.185610/#post-2253277
QUESTION FOR JEFF OR THOSE IN AUTHORITY: IS IT OK TO COPY AND PASTE FROM A GOOGLE AI SEARCH? That is what I did below. If NOT, Delete the part below from "AI Overview", and everyone can see it by clicking on the link.
I did a search on paint compatibilities and it came back with some good information but said nothing about shellac, and when to use it or when not to use it, so I revised the search to include shellac. Below is the results of the search. This is a thread that some of you might want to mark or tag for future reference.
This does NOT say anything about CA either, but we do know that CA does work over shellac and some other paints. The main question is what other paints and situations to use or not use. ALSO, Oily woods present difficult situations many cases, and again, Shellac is the go to under finish. Alcohol or acetone will clean the oil off of the surface, if shellac (dewaxed) is not used.
Google search on paint compatibilites
https://www.google.com/search?q=paint+compatibilities+as+to+what+paints+work+over+or+with+other+paints,+including+Shellac,+and+what+not+to+do?&sca_esv=4dde0993aef9cf17&biw=1300&bih=794&aic=0&sxsrf=ANbL-n4or-AfmLGvg5hLBhT2pye8rk_SoQ:1770058438205&ei=xvKAabeRDIHUp84PtJ6vwA0&ved=0ahUKEwi3jMPDvbuSAxUB6skDHTTPC9gQ4dUDCBE&uact=5&oq=paint+compatibilities+as+to+what+paints+work+over+or+with+other+paints,+including+Shellac,+and+what+not+to+do?&gs_lp=Egxnd3Mtd2l6LXNlcnAibnBhaW50IGNvbXBhdGliaWxpdGllcyBhcyB0byB3aGF0IHBhaW50cyB3b3JrIG92ZXIgb3Igd2l0aCBvdGhlciBwYWludHMsIGluY2x1ZGluZyBTaGVsbGFjLCBhbmQgd2hhdCBub3QgdG8gZG8_SABQAFgAcAB4AJABAJgBAKABAKoBALgBA8gBAPgBAZgCAKACAJgDAJIHAKAHALIHALgHAMIHAMgHAIAIAA&sclient=gws-wiz-serp
AI Overview
Almost any paint can be applied over another, provided the surface is properly cleaned, de-glossed (sanded), and, when necessary, sealed with a compatible primer. Shellac, particularly dewaxed shellac (like Zinsser BIN), serves as a "universal" bonding primer that adheres to almost any surface and accepts almost any topcoat.
Here is a guide to paint compatibilities, covering shellac and other common finishes.
Shellac Compatibility
General Paint Compatibility Rules
What NOT to Do (Incompatibilities)
Summary Table of Common Pairings
Best Practices for Success
Other may have some more technical information or even some corrective information. I am not here to be the one that knows it all but I enjoy learning what is right and true in whatever situations - from others.
Fine Engineer-Jeff. "Oak with Oil Based Stain and CA Finish'
https://www.penturners.org/threads/oak-with-oil-based-stain-and-ca-finish.185610/#post-2253277
QUESTION FOR JEFF OR THOSE IN AUTHORITY: IS IT OK TO COPY AND PASTE FROM A GOOGLE AI SEARCH? That is what I did below. If NOT, Delete the part below from "AI Overview", and everyone can see it by clicking on the link.
I did a search on paint compatibilities and it came back with some good information but said nothing about shellac, and when to use it or when not to use it, so I revised the search to include shellac. Below is the results of the search. This is a thread that some of you might want to mark or tag for future reference.
This does NOT say anything about CA either, but we do know that CA does work over shellac and some other paints. The main question is what other paints and situations to use or not use. ALSO, Oily woods present difficult situations many cases, and again, Shellac is the go to under finish. Alcohol or acetone will clean the oil off of the surface, if shellac (dewaxed) is not used.
Google search on paint compatibilites
https://www.google.com/search?q=paint+compatibilities+as+to+what+paints+work+over+or+with+other+paints,+including+Shellac,+and+what+not+to+do?&sca_esv=4dde0993aef9cf17&biw=1300&bih=794&aic=0&sxsrf=ANbL-n4or-AfmLGvg5hLBhT2pye8rk_SoQ:1770058438205&ei=xvKAabeRDIHUp84PtJ6vwA0&ved=0ahUKEwi3jMPDvbuSAxUB6skDHTTPC9gQ4dUDCBE&uact=5&oq=paint+compatibilities+as+to+what+paints+work+over+or+with+other+paints,+including+Shellac,+and+what+not+to+do?&gs_lp=Egxnd3Mtd2l6LXNlcnAibnBhaW50IGNvbXBhdGliaWxpdGllcyBhcyB0byB3aGF0IHBhaW50cyB3b3JrIG92ZXIgb3Igd2l0aCBvdGhlciBwYWludHMsIGluY2x1ZGluZyBTaGVsbGFjLCBhbmQgd2hhdCBub3QgdG8gZG8_SABQAFgAcAB4AJABAJgBAKABAKoBALgBA8gBAPgBAZgCAKACAJgDAJIHAKAHALIHALgHAMIHAMgHAIAIAA&sclient=gws-wiz-serp
AI Overview
Almost any paint can be applied over another, provided the surface is properly cleaned, de-glossed (sanded), and, when necessary, sealed with a compatible primer. Shellac, particularly dewaxed shellac (like Zinsser BIN), serves as a "universal" bonding primer that adheres to almost any surface and accepts almost any topcoat.
Here is a guide to paint compatibilities, covering shellac and other common finishes.
Shellac Compatibility
- What works over Shellac: Almost any paint, including latex, acrylic, oil-based, and alkyd paints, can be applied over shellac-based primer. It is excellent for covering knots, stains, and odors.
- What works over traditional (waxed) shellac: Oil-based varnishes and paints work fine. If using a water-based finish, ensure the shellac is dewaxed.
- What to avoid: Do not use shellac-based primers on exterior wood surfaces, as they are too brittle and may crack.
- Crucial Tip: Let shellac dry thoroughly (at least 45 minutes to 24 hours depending on humidity) to avoid fish-eye issues or trapping solvents.
General Paint Compatibility Rules
- Latex/Acrylic over Oil: Possible, but requires surface prep. The oil-based surface must be cleaned, sanded, and coated with a bonding primer.
- Oil over Latex: Generally, this is not recommended. Oil-based paint is rigid and may crack if it expands or contracts over the flexible latex underneath.
- Chalk Paint over Old Paint: Works well, but should be sealed with a topcoat, as it is porous.
- Vinyl Bottom Paint over Non-Vinyl: Do not do this; the solvents in vinyl paint will cause the previous layer to detach.
What NOT to Do (Incompatibilities)
- NEVER skip cleaning: Dirt, grease, and wax will prevent adhesion regardless of the paint type.
- Don't apply thick coats: Multiple thin coats are better than one thick coat, which can lead to cracking or "alligatoring".
- Don't put Water-Based over Wet Oil: Ensure oil-based paints are completely cured (not just dry) before applying water-based products, or the surface may crack.
- Avoid using Shellac in high-moisture areas: It can crack in bathrooms.
Summary Table of Common Pairings
Surface / Old Paint | Recommended Primer/Prep | Compatible Topcoat |
Shellac (BIN) | None (is the primer) | Water-based, Oil, Acrylic, Alkyd |
Oil-Based Paint | Sanding + Bonding Primer | Latex, Acrylic, Oil |
Latex/Acrylic | Light Sanding | Latex, Acrylic |
Varnish/Poly | Sanding / De-waxed Shellac | Oil-based, Water-based |
Raw Wood | Shellac (for knots) | Almost anything |
Best Practices for Success
- Clean: Use a degreaser or soap and water.
- De-gloss: Use 180-220 grit sandpaper to scuff the surface.
- Prime: Use a high-quality primer (e.g., Shellac-based for stains, Bonding primer for oily/shiny surfaces).
- Test: Apply the new paint to a small, hidden area to check for adhesion or, in the case of spray paint, "crinkling" (incompatibility).
FAQs About Paint Compatibility When Switching Between Brands or Types
https://randalls.ca/blogs/faq/faqs-...S2ez7wzaquIB-iy0JKusXsis42OsIGTXn2e00P9KgrH25Other may have some more technical information or even some corrective information. I am not here to be the one that knows it all but I enjoy learning what is right and true in whatever situations - from others.
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Excellent