Painting - Changing the sheen from semi-gloss to flat

Started painting house with semi-gloss alkyd (tinted tan color). I've used three gallons and have two left. Now that I've seen it on a section of the house, I've changed my mind on the sheen--I need a flat sheen.

1. Is there a way to lower the sheen on the two unused gallons (can't get my money back)? For example using an additive or mixing it with an oil based primer?
2. Is there any problem painting a flat as the second coat?

Welcome to the forums

SWP has a gloss modifier that I have used in the past. I don't know if it is still available.

If the paint has not been custom mixed [tinted] you should be able to take it back. Just reread your post, since it was tinted, you can't take it back.

I don't know if you can still buy flat oil base paint. To recoat oil base enamel with flat latex you would first need to sand and coat with a solvent based primer first.

I am pretty sure the gloss modifier was/is only availble by the gallon, and it runs about $50. (It's been awhile). However, to go from a S/G to a flat would take a HUGE amount of modifier. By the time you introduce enough to lower the sheen, you will have ruined to paint. It is best for lowering sheen a few degrees, not 30-60 degrees that the OP is looking for. If I remeber correctly it was mainly used by blending facilities for woodworking shops and didn't weather particularly well on the outdoors. Mainly used to match the sheens of lacquers and pre-cat lacquers.

BTW it is horribly thick and smells terrible. You would need the paint store to put it on the shaker for you, as it is not easy to drill into the coating.

I would just bite the bullet and buy some flat oil. There should be no problem topcoating the S/G. Use the remaining as a sort of primer for the next coat.

Incedently why did you go w/oil on the exterior? More of a thought process question, not a judgement question.

I would just bite the bullet and buy some flat oil. There should be no problem topcoating the S/G. Use the remaining as a sort of primer for the next coat.

Incedently why did you go w/oil on the exterior? More of a thought process question, not a judgement question.

Thanks guys. Sounds like I'll just use the remainder for rest of the first coat and buy new flat for the second coat.

The reason I went with oil was because that is the paint my dad said to use.

When your dad was young, oil was the way to go. With the EPA getting involved, oil based paint isn't as good as it used to be and latex paint has improved dramatically, making it the better choice now most of the time.